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SUMMER ASSIGMENT FOR CLASS 10TH
SUBJECT ENGLISH
LESSON NO. 8
(The Ghat of the only world)
thinking about text
Q.No.1 What were the common things between Ghosh & Shahid ?
Ans The common things between Ghosh & Shahid were that they both loved Roganrosh,
Begum Akhtar & Kishore leumar. They had a natural indifference to cricket & has
attachment to old Bombay films.
Q.No.2 What are things that Shahid loved ?
Ans The things that Shahid loved are; food, Bombay films, Roshan Ara Begum & KIshore
Kumar. He had a friendly nature & had often party in his living room.
Q.No.3 How does Shahid face death ? Describe the hospital scene ?
Ans Shahid faced his death with big courage & challenge. He was never scared of it. He
thought he was to meet with his moths after death.
Once before his death he was in hospital & escort brought a wheel chair far him but
he would him away & said to him he was strong often to walk on his own when he
walked few steps his knees buerles then Iqbal ran baer for the wheel chair. Heaming,
aganist the hospital wall, a kind of joy come upon him, when the hospital orderly
returned with the wheel chair,he gave him smile & asked where he was from. The man
said that he was from spacis. He clapped his hands & said at the top of his voice that he
always want to learn Spanish
Q.No.4 Who is James Merill ?
He is a poet who radically alter Shahids style of writing poetry & often this started
experimenting with strict metrical patterns & verse forms.
Q.No.5 Pick out the elements of humour from the lesson ?
Ans Shahid was aline & jouial person. He was approaching to death but he didn’t loose
his heart. Once in hospital escort orderly brought a wheel chair for him as he was too
wear to stand but with a big smile he waved his own. Also once he met with a lady who
get too irritated by him & she asked him whether he was carrying anything dangerous
to the passengers. He clapsed his hand to his chest & answered only his heart.
Q.NO.6 What facilitated Ghosh to fulfil his pledge ?How did it help him ?
Ans Ghosh had pledged to Shahid that he wanted to write about him after his death ‘to
fulfil his pledge’ Ghosh started keeping a record of every moment that he spent with
Shahid. He also gathered all the information that he could about Shahid’s life. All this
helped him to fulfil his pledge.
Q.No.7 How was shahid’s reputation as a teacher among his students ?
Ans Shahid’s students ordered him . They held him in deep love & respect. For some
time he caught at Mahattan’s Baruch college. When he was to leave this college, the
students printed a magazine & dedicated the issue to him .
Q.NO.8 What does “ the ghat of theonly world” man ?
Ans ‘Ghat’ is a Hindi word which means the place at a river bank from where boats sail
off with passengers for the other bank. Here ‘the only world’ is a symbol of man’s life on
this earth & the ‘Ghat’ is the bank ( point of death) from which man sails off for other
world
Chapter No.4
Short story
out of business
Q.No.1 Do book & writing work by yourself
Thinking about text
Q.No.1 What was Rama Roa’s business ? How did it collapse ?
Ans Rama Rao worked as the Malgudi agent in a Grama phone company. He had put
little money as a security in that agency . It collapsed due to the failure of the bank by
which the factory in northern India automatically collapsed.
Q.No.2 What effect did it have on him & his family ?
Ans He was totally wreck due to the collapse. He found himself in the street. He had
little money in the bank & same stock on hand, but the stock moved out slowly. Then he
applied for refund of his security but all in vain.
Q. NO.3 What is the ‘stock’ referred to in line 13 ?
Ans ‘Stock’ referred the stock or things of gramophone recoeds .
Q.NO.4 Why did Rama Rao worry les about his family after he came across the captain ?
Ans Rama Rao worried less about his family after coming across the poernal namely
‘The captain’ because all the ten Rama Rao remained losed in thinking the ansewed. to
be filled in the puzzle . He became indifferent to his wife & children. He wanted even
quarrel with his wife to ave his rupee for the next entry.
Q.No.5 Why did Rama Rao decided to send it at least four entries for the “special offer”
cross word competition ?
Ans Rama Rao decided to send in at least 4 entries for the special offer cross word
competition because o huge amount that is 8000 instead of 4000.
Q.No.6 Why did Rama Rao plan to go to Madras ?
Ans Rama Rao planned to go to Madras in order to find some suitable job for himself. He
wanted to move back to his Banglow & gave all comforts to his family like before.
Q.No.7 What made Rama Rao belive the God had shown him mercy ?
Ans Due to his failure, he decided to end his on the railway line. He started walking
along the line & reached a few miles from the town . There he lay down across the line,
he laid there for few minutes but the train did not come. Then he get up & moved
towards station their he came to know that the train was 3 hours late due to accident.
In this way he thought that God had shown him mercy.
Q.No.8 How did Rama Rao alternate between hope & despire ?
Ans Rama Rao hoped to over come his financial difficulties through cross word puzzles
competition. He would send in entry every week but all in vain , then he was filled with
despair. Everytime he faced failure. Thus Rama Rao alternated between hope &
despair.
Chapter No.5
The servant
Thinking about text.
Q.No.1 Why had Gerasim been going about in vain in the village ?
Ans Gerasim has been going about in vain in the village because he couldn’t find out
job any where so every where he heard no or not yet.
Q.No.2 Where had Gerasim been working ? Why did he return to village ?
Ans Gerasim had been working in his own village mean while he was called for military
duty but there he wasn’t drafted later. So, why he had to return back to his village.
Q.No.3 What did the coach man tell Gerasim when he narrated his story ?
Ans When Gerasim narrated Yegor the whole story he started prasing his master. He
promised Gerasim that he will try to give him work at his merchants place as there was
on old man who couldn’t work now.
Q.No.4 How did the coachman persuade his master to employ Gerasim ?
Ans The coachman persuaded his master to employ Gerasim by him the boy whom he is
requesting for is very punctual, dutiful & would do every thing.
Q.No.5 Why was the master reluctant to disengage old servant ?
Ans The master was reluctant to dis engaged the old servant because he had been
working there since a long time & it would be sin to remove him. He totally disagreed
but still he told the coach man he will consider the matter.
Q.No.6 What did Gerasim hear while crossing the yard ?
Ans Gerasim heard very hard & tough words that made his heart bleed ?
The old, woman as cursing her faith as her husband was being
removed by the job & they had no other way then begging but she was too sayin that
there master wasn’t bad it was the coachman who provoked him.
Q.NO.7 What did the old couple think about the master ?
Ans The old couple thought that the masters are very cruel & rough & had no sense of
justice & they removed their servants when they liked.
Q.No.8 What was the effect of the old couple’s conversation ? On Gerasim
Ans The old couples conversation had a worse effect on Gerasim & there he decided he
won’t ata place where it would be unfair & injust because of him.
Q.No.9 How does the story reflect the humility of Gerasim ?
Ans Gerasim was a kind hearted man. He had a heart which throbbed with sympathy
for others. When he heard the voice of an old woman, it hurt his heart . He decided not
to work there as it would be unfair to be cause of removal of the couple.
Q.No.10 Do book work & writing work by your self.
Q.No.1 Do book & writing work by yourself
Chapter No.4
Short story
out of business
Thinking about text
Q.No.1 What was Rama Roa’s business ? How did it collapse ?
Ans Rama Rao worked as the Malgudi agent in a Grama phone company. He had put
little money as a security in that agency . It collapsed due to the failure of the bank by
which the factory in northern India automatically collapsed.
Q.No.2 What effect did it have on him & his family ?
Ans He was totally wreck due to the collapse. He found himself in the street. He had
little money in the bank & same stock on hand, but the stock moved out slowly. Then he
applied for refund of his security but all in vain.
Q. NO.3 What is the ‘stock’ referred to in line 13 ?
Ans ‘Stock’ referred the stock or things of gramophone recoeds .
Q.NO.4 Why did Rama Rao worry les about his family after he came across the captain ?
Ans Rama Rao worried less about his family after coming across the poernal namely
‘The captain’ because all the ten Rama Rao remained losed in thinking the ansewed. to
be filled in the puzzle . He became indifferent to his wife & children. He wanted even
quarrel with his wife to ave his rupee for the next entry.
Q.No.5 Why did Rama Rao decided to send it at least four entries for the “special offer”
cross word competition ?
Ans Rama Rao decided to send in at least 4 entries for the special offer cross word
competition because o huge amount that is 8000 instead of 4000.
Q.No.6 Why did Rama Rao plan to go to Madras ?
CLASS 10 TH
SOCIAL STUDIES
CHAPTER 7
OUTCOMES OF DEMOCRACY
QUESTIONS & ANSWEQ
,NO.1 How does democracy produce an accountable, responsive and legitimate
government?
Ans: Democracy produces an accountable government as the people have the right to
choose their representatives through the electoral process. After coming to power of
these elected representatives don’t work in a proper way people have the right to
question the government either directly or through media and even through judiciary.
Also people have the right not to elect them in the next election.
Democracy produces a responsive government as it promotes the formation of public
opinion and is sensitive and responsive to the needs and expectations of the people. It
allows open public debate on measure policy and legislations and citizens right to
information.
Moreover, the periodic practical participation of people in the electoral process for a
democratic government provides legitimacy to the very same government.
Q.NO.2 Give arguments to support or oppose the following assertions:
I) Industrialized countries.........
Ans: If we consider democracy and dictatorship regives between 1950-2000, we find
countries under dictatorship to be more advanced, economically. However, the
difference in the rates of economic development between less developed or poor
countries with dictatorships and democracies is negligible but the countries like India
has become one of the fastest growing economies of the world, under democracy and
Zimbabwe has run into huge international debits under Robert mugabs rule. Thus. It is
not always proper to say that the poor need dictatorship to become rich.
II) Democracy cannot reduce inequality of incomes between different citizens.
Ans: There is no denying fact that we find growing economic inequalities in
democracies. However, the democratic governments play an important role in removing
economic disproperties. In India the schemes like Indira Awas yojna, Bharat nirman
yojna, MGNREGA etc, have been devised to generate employment and reduce poverty
in the country.
III) Government in poor countries should spend less on poverty reduction, health,
education and spend more on industries and infrastructure.
Ans The governments in poor countries should maintain a balance between the
investment on poverty reduction, health education & on industries & infrastructure, so
that every institution of the country gets an assistance from the government to develop
itself.
iv) In democracy all citizens have one vote, which means that there is absence of any
domination & conflict.
Ans A democracy gives every citizen & every social group equal importance to avoid any
domination & conflict in the society. How ever conflicts are not totally absent in a
democracy . Democracy only evoids the possibility of such conflict by giving equal rights
to everyone.
Q.No.3 Identify the challenges to democracy in the following deseriptions. Also suggest
policy / institutional mechanism to deepen democracy in the given situations ?
i) Following a height court directive ..............
Ans Challenge involved : challenges of social inequality & untouchability suggestion:central government, in this regard, has directed the state government not to predice
untouchability in any form. If any one tries to do so, he will be punished under the
law of untouchablity Offence act, 1955.
ii) A large number of farmers are committing suicide in different states of India.
Ans Challeng involved challenges of poverty & economic in equalities suggestion: for
this purpose, cooperative socities should come forward to help the poor farmers. Crop
insurance policy should be implemented for any eventuality of crop failure.
iii) Following the allegation of killing ..............
Ans Challenge involved :- challenge to preserve the peoples trust in government
agencies, like the police.
Suggestion:- to check such challenges in a democratic government the law should be
amended so that the police man. Do not violate law & order by themselves & should
have a reasonable behaviour towards the civilians.
Q.No.4 Read the passage below:
i) What does Nannu’s example show ?
Ans Nannu’s example shows the importance of the right to information act
ii) What impact did Nannu’s action have on Officials ?
Ans On filling an application under the right to information act, by nannu, it created a
great impact. Within a week, an official from food department visited his house to
inform him that the card had been made & he could collect it in working day. On the
next day, Nannu received his new ration card.
Ans My parents had mixed experience about the government officials when they
approach for their problems. Some officers took a prompt action & were very helpful
but in some cases they faced difficult situations as some officers showed reluctan to
take a quick action.
Q.NO.5 What are the conditions under which democracies accommodate social
diversities ?
Ans The social diversities with respect to caste, race, religion, language etc. Are present
almost in every in every country, globly of government to provide a suitable from of
government to accommodate these diversities. Democracy aims at giving equal rights &
equal opportunities to all the citizens despite social diversities. Similarly it shows respect
for social diversities & provides a mechanism to negotiate many soial differences.
Democracys principle ‘rule by majority means that in case of every decision or in case
of every election, different persons & groups can form a majority again inspite of scial
diversities. Infact, if some is barred from being in majorityon the basis of birth, , colour
etc, thsen the democratic rule cases to be accommodative for that groups.
Chapter No . (4) Gender , religion & caste
Q.No.1 Write a few sentences about each of the following
1) Margret Thetcher: this lady was born in Oct. 1925 &, later become the first women
prime Minister of united Kingom she implemented such policies that have come to be
known as the Thatcherism. She was nicknamed as ‘Iron lady’ because of her
uncompromising politics & leadership style.
2) Indra Gandhi: this lady was born on 19th Nov.1917 in Allahabad. She became the first
female Prime Minister of India. She will be remembered for her commendable efforts in
the development & progress of science, space exploration irrigation as well as policies
like nationalisation of banks in India.
3) Benezir Bhutto : Benazir Bhutto was the first women Prime Minister of Paskistan. She
was born on 21 June 1953. She drove initiations for Pakistan’s economy & national
security. She implemented social- capitalist policies for industrial development in
Pakistan.
4) Khalida Zia : Begum Khalid Zia is a Bangladeshi politician. She was the first women
Prime Minister of Bengladesh . She was born on 15, Augest 1945. She took various
measures for the development of Bengladesh in the field of education,health, industry
& infrastructure .
5) Sheikh Haseena : Shiekh Haseena is the present prime Minister of Bengladesh since
2009.She led the Bengladeshi Awemi league from 1981. This lady also various
ninitiatives for the development of her country.
Chapter No.(8) Challenges to Democracy
Q.No.1 What do you understand by counter- productive law ?
Ans If there is any legal change, by making a new law or improving an existing law, it
must be carefully observed what results it will have on politics. Sometime the results
may be counter- productive. For example many states in India have banned people who
have more then two children from contesting Panchayat elections. This has resulted in
denial of political opportunity to many people in the country, although, which was not
intended in the beginning. Thus a counter-productive law is a making & application of
such a law the result or outcome of which is opposite or contrary to that what was
indended.
Q.No.2 Explain the challenges faced by democracy like foundational challenge.
Challenge to expansion of democracy & deeping of democracy.
Ans The different challenges faced by democracy in different parts of the world are
mentioned as under:
1) Foundational challenge: countries that do not have the democratic set-up face
the challenge of making a transition to the democratic typeof government.
i) First of all, non democratic regimes have to be brought down.
ii) Secondly, all attempts shall be made to establish a sovereign & functional state.
iii) Thirdly, the military should to rept away from controlling the government
2) Challenge to expansion : democratic countries face the following challenges of
expanding democracy to various social groups & regions
i) Such countries need to endure that more social groups, regions & institutions
follow democracy in their functioning.
3) Deepening of democracy : this challenge is faced by all the democracies . It
involves strengthening of the institutions & practises of democracy. It usually
means peoples participation & control in the government. It requires an attempt
of checking the control & influence of wealthy & powerful people i the
governmental decision.
Q.No.3 What do you mean by a political reform & what are the different political or
democratic reforms that should be implemented in India ?
Ans All the suggestions or proposals about over coming various challenges to
democracy are called democratic or political reform
The different political reform that should be implemented in India are mentioned
as under
i) Legal & constitutions reforms : as some of the acts have become obsolete ( or
out dated)& which need to be amended as per the current needs.
ii) The anti-corruption’ Jan Lok Pal Bill’ must be passed to check corruption all from
the political circles & bureaucracy upto the local institutions.
iii) It includes redressing regional imbalances.
iv) Sustainable development in terms of economic, social & environmental reforms
v) More over, the democratic or political reforms can be implemented through
poltical practice, i.e ,an active political participation by ordinary citizens of
the country.
ECONOMICS
LESSON NO. (2) SERVICE SECTOR
Q.No.1 Identify places of religious pilgrimage in J & K ?
Ans The state of J & K has potential of religious tourism the places of religious
pilgrimage are found in all the three regions of the state. The places of religions
pilgrimage in J & K are Shadara Shareef, Hazratbal shine, Jamia Masjid Srinagar,
Shankarcharya temple, Guudwara Chalti Patshahi, Khir Bhawani temple, Hemis gompa
Amarnath cave & Mata Vishno Devi shrine.
Q .No.2 Write down the main principles of ppp ?
PPP stands public private partnership in which peivate enterprise help the government to
undertake development project by sharing profits. It emphasised to engage the youth &
run special training programmes to chance employability of 8000 youth perannce in J &
K over a five year period.
Q.No.3 What is the role of handicraft sector in employment generation in J & K ?
The handicraft sector played a great role in employment in J & K . The handicraft sector
in J & K occupies an important place with a fine radition of craftman, employing 4-5 lakh
artisans, 70 major craft clusters & revenue generating of Rs 1000 crore plus. Highly
labour intensive the sector contributes significantly due to lack of Kashmir branch, poor
quality control, exploitative middle men competition from machine made fabrics.
Q.No.4 Write a note on Micro small & medium scale industries in employment
generation
The role of micro, small & medium scale industries in the employment generation is well
established. This sector has not done well in the state due to number of reasons including
inadequate local demand, poor credit flows & distance from market the private
investment & large industry also bringing sustainable growth & jobs to youth of the state.
Q.No.5 How employment potential in j & K can be increased
Ans The employment potential in J & K can be increased through the following ways:
1) Accelerating the rate of economic growth of the state
2) More effective implementation of employment oriented schemes &
programmes
3) Extending support to entrepreneurs to set up small & medium enterprises for
employment.
4) Food processing etc should be revived & promoted
5) The tourism & construction sectors would generated substantial additional
employment & there sectors should be promoted in the state.
Q.No.6 Name the programmes conducted by Infosys development centres
Ans The faculty enchancement programme (FEP) conducted by the Infosys
c\development centers trained 4900 faculty members from engineering institutions of J
& K state. The important dimension of this is the interaction of the academicians with the
industry to understand their expectations of entry level students skilled
LONG ANSWERS
Q No.1 Discuss the role of tourism in generating employment J & k ?
Ans Tourism is a great potential in generating Employment in J & K. The state has been
benefitted from the tourism manifold. The state of J & K is an important tourist
destination & has been a place of attraction for tourist since centuries. The tourism helps
in developing backward & rural areas into prosperous developing areas.
Tourism generates employment, though it is difficult to measures or calculate the
employment generation as there jobs are scattered. The tourism industry helps in
expansion of employment opportunities as it is labour intensive industry in which we
find different types of employment for skilled, Sami skilled & unskilled persons. It
generates large scale direct & indirect employment, in the number of hotels, restaurants,
house boats, transport pervices, gude agents & so on.
Q.No.2 Write down sectoral initiatives by the government to grnerate employment in J &
K?
The sect oral initiatives taken by the government to generate employment in J & K are
as
1) The highly labour intensive live stock sector & absorb large number of skilled &
Unskilled workers is important to the J & k. The initiative was taken to increase
the employment potential of the sector & attract private investments.
2) The tourism sector with its potential in employment generation, the state
government must in place PPP policy that will address land related concerns a
practical manner for the tourism sector especially in creating hotels & resorts.
3) In the growth of Micro small & medium enterprises sharp focus was laid on
improving access to finance by reviving the J & K state financial corporation,
increasing the scope of prime minister employment guarantee programme &
purchases preferences in government procurement will help the revival of this
sector in J & K.
CLASS 10TH
SUBJECT ;SCIENCE
TOPIC ACIDS BASES AND SALTS
Chemical substance is a form of matter that has constant chemical composition and
characteristic properties. Chemical substances are often called pure to set them apart from
mixtures. A common example is pure ‘water’. It has the same properties and the same
ratio of hydrogen and oxygen whether it is isolated from a river or made in laboratory.
The two main sources of most sources of the chemical substances are:
1) Animals and plants
2) Minerals and rocks
The chemical substances obtained from plants and animals (living organisms) are called
organic compounds. And
The chemical substances obtained from minerals and rocks are called Inorganic
compounds.
The earliest classification of inorganic compounds including a large number of organic
compounds was on the basis of their taste. On the basis of their taste, the compounds
were classified into three categories:
1) Acids
2) Bases.
3) Salts
ACIDS:
The term acid has been derived from the Latin word, ‘acidus’ which means sour.
Some of the definitions of acids are
On the bases of taste, acids are the substances which have sour taste.
According to Arrhenivs concept (1884), acids are those compounds which contain
Hydrogen & which when dissolved in water give hydrogen ions (H+) in the solution.
Or
According to arrhenvis definition acids are the substance which give hydrogen.
HCL(aq)-------------H+(aq) + cl-(aq)
Acid ( Hydrochloric acid)
Hydronium ions
Chloride ions
+
-(aq)
HNO3(aq)----------- H (aq) + NO3
Acid (Nitric acid)
Nitrate ions
H+ ions don’t exist as such in solution. They combine with water molecules re-exist as
hydronium ions.
According to ‘Bronsted-lowry’ concept (1923), acid is a substance that denotes protons
(H+).
Or
Acid is asubtance which gives up proton (proton-donar).
PROPERTIES OF ACIDS: a) PHYSICAL PROPERTIES:
1) All the acidic substances almost have a sour taste.
2) Actions on litmus paper: acids turn blue litmus solution red.
3) Action on methyl orange: methyl orange turns red when 1-2 drops of its solution
are added to the solution of an acidic substance.
4) Corrosive nature: most of acids are corrosive in nature. They produce a burning
sensation on the skin and holes in the clothes on which they fall.
They also attack metal structure and stone work. Hence, the are never
stored in metal containers. They are always stored in containers made of
glass or ceramics as they are not attacked by the acids.
B) CHEMICAL PROPERTIES:
1) Reaction with metals: Acids react with active metals like zinc, magnesium etc.
generally with the evolution of hydrogen gas. The reaction may be represented as follows
:
Zn(s)+dil.H2SO4 (aq)--------------ZnSO4(aq) + H2(g)
Zinc Sulphuric acid
Zinc sulphate
Hygrogen
Zn(s) + 2Hcl (aq)----------------Zncl2(aq) + H2(g)
Zinc Hydrochloric acid
Zinc chloride
The compounds formed such as znso4, zncl2, are called salts. Thus , in general metal +
acid -------metal salt, hydrogen gas.
REACTION WITH METAL CARBONATES AND METAL HYDROGEN
CARBONATES(BIO-CARBONATE):
Acids react with metal carbonates and bio carbontes to give out carbon dioxide
effervescence and forming the corresponding salt and water. Example,
Na2Co3 + H2So4 ------------------------ Na2So4 + H2O +Co2
Sodium carbonate Sulphuric acid
Sodium sulphate
NaHCo3 + Hcl
------------Nacl + H2o +Co2
Sodium hydrogen carbonate Sodium bi carbonate Sodium chloride
Thus, in general
Metal carbonates or Hydrogen Carbonate + Acid ------------ salt +Co2 + H2O
CONDUCTION OF ELETRICITY:
The solution of acids in water conducts electricity.
REACTION WITH BASES:
When acid reacts with a base. It forms salt and H2o. As a result, the acidic properties
disappear. The process is called neutralization.
Hcl + Naoh -------------- Nacl + H2O
Hydrochloric acid sodium hydroxideSodium chloride
water
REACTION WITH METAL OXIDES:
Metal oxides like quick lime, i.e. calcium oxide (Cao), copper (II) oxide (CUO),
magnesium oxide (Mgo) etc react with acids to form salt and water. Examples,
CaO(s) + 2Hcl (aq) ------------- Cacl2 + H2O
Calcium oxide
Calcium chloride
CuO(S) + 2 Hcl(aq) ------------ cucl2 + H2o
Copper (II oxide Hydrochloric
Copper(II)
In general, we can write the reaction as:
Metal oxide + acid ---------------- Salt + water
ORGANIC ACIDS:
Acid present in living organisms ( i.e. plants and animals) are called organic
acids. They are naturally occurring acids. They are generally weak acids and are used in
food-stuff.
Some naturally occurring acids and their sources are given below:
S.no.
Natural Source
Acid Present
01
Oranges, Lemon
Citric acid
02
Apple
Malic acid
03
Tomatoes
Oxalic acid
04
Tamarind(imli)
Tartaric acid
05
Sour milk or curd
Lactic acid
06
Vinegar
Acetic acid
07
Proteins
Amino acid
INORGANIC (MINERAL) ACIDS:
Acids obtained from minerals of earth are called mineral acids. They aren’t naturally
occurring acids but are prepared in laboratory or manufactured in the industry.
The three most commonly used mineral acids are Hydrochloric acid, sulphuric acid &
nitric acid. These are strong acids. Some inorganic acids are weak acids e.g. carbonic
acid, phosphoric acid etc strong acids are very dangerous to skin and delicate parts of the
body.
CHEMICAL FORMULAS OF SOME COMMON ACIDS:
1) Hydro chloric acid- Hcl
4) Sulphuric ACID- H2So4
2) Acetic acid – H2SO4
5)Formic acid- HCOOH
3) Nitric Acid – HNO3
6)Carbonic Acid – H2CO3
USES OF ACIDS:
Organic acids and inorganic acids
1) Acidic acid Vinegsr: is used as preservative in making pickles.
2) Tatric acid: is an ingredient of baking powder &
3) Carbonic acid: is present in soft drinks and soda water
4) Sulphuric acid: is one of the most important chemical used by a large number of
industries. Hence, it is called the “king of chemicals”. It is used in manufacture of
fertilizers like ammonium sulphate, in petroleum refining, in manufacturing of
paints, explosives, synthetic fibres, dyes, drugs etc and in storage batteries.
5) Nitric acid: is used in manufacture of fertilizers like ammonium nitrate,
explosives like TNT, artificial silk, dyes, plastics.
6) Hydrochloric acid: is used for cleaning the surface of metals before being
electroplated or galvanized and in removing scale deposits from inside the
boilers. It is used in textile, food, leather and dye industries.
BASES:
DEFINITION:
On the bases of taste, bases are defined as the substances which are bitter in taste.
According to Arrhenius concept (1884), bases are those compounds which ciontain
hydroden and which when dissolved in water give hydroxide ions (OH-) in the solution.
Or
According to Arrhenius definition, bases are the substances which give hydroxide ions
(OH-) in aqueous solution.
NaoH(aq) ------------ Na + (aq) +OH-(aq)
Base
According to ‘Bronsted-Lowry’ concept (1923), base is a substance that accepts protons
(H+)
Or
Base is a substance which accepts protons.
PROPERTIES OF BASES:
a) Physical Properties:
1) Bitter taste: Bases posses a bitter taste
2) Slippery or soapy touch: They posses a slippery touch like soaps
3) Action litmus paper: they turn red litmus blue
4) Action on phenolphthalein: they turn phenolphthalein solution pink
5) Corrosive nature: some bases like caustic soda(sodium hydroxide), caustic
potash (potassium hydroxide) etc produce burning sensation on the skin. You
are therefore advised never to touch or taste any base.
6) Conduction of electricity: like acids, the solution of bases in water also
conduct electricity.
b) Chemical properties:
1) Reaction with acids: bases react with acids to form salt and water. The
process is called neutralization. As a result, the base loses its properties. E.g.
2Naoh(aq) + H2So4(aq) ------------- Na2So4(aq) +2H2o (L)
Sodium hydroxide (base) Sulphuric acid (Acid)
Sodium Sulphate (salt)
Water
2) Reaction with metals: some bases like sodium hydroxide and potassium
hydroxide react with active metals like zinc and almunium to liberate
hydrogen gas along with the formation of a salt. Thus,
2Naoh + Zn ---------------- Na2zno2 + H2
Sodium Hydroxide
Zinc Sodium Zincate
Hydrogen
2Naoh + 2Al + 2H2O ------------- 2 NaAlo2 + 3h2
Sodium Hydroxide Almunium
Water Sodium aluminate
Hydrogen
3) Reaction with non metal oxides: bases react with non metal oxides (like Co2,
So2, So3,P2o5 etc) to form salt and water
Base + non-metalic oxide ------------- salt + water
For example,
Ca(oh)2 + Co2 ------------- CaCo3 + H2o
STRONG AND WEAK ACIDS:
Strong acids: The acids which are completely ionized in water and produce large
amount of hydrogen ions are called strong acids,
Hydrochloric acid (Hcl), sulphuric acid (H2SO4) and nitric acid (HNO3) are strong
acidc because they completely ionize in water. E.g.,
Hcl(aq)---------- H+(aq) + cl- (aq)
H2SO4(aq) --------- 2H+ (aq) + SO42-(aq)
HNO3(aq) ---------- H+ (aq) + NO3-(aq)
Weak acids: The acids which are partially ionized in H2o and thus produce a
small amount of hydrogen ions are called weak acids.
Acetic acids (CH3Cooh), carbolic acid (H2Co3) and sulphurous acid (H2SO3) are
weak acid because they partially ionize in water.
STRONG AND WEAK BASES:
Strong base: The base which completely ionize in water and produce large
amount of hydroxide ions(OH-ions) are called strong base.
Sodium hydroxide (Naoh) and potassium hydroxide(KoH) are strong bases, e.g.
Naoh(aq)------------ NA+(aq) + Oh-(aq)
KOH(aq)------------ K+ (aq) + Oh- (aq)
Weak Bases: the bases which partially ionizes in water and thus produce small
amount of hydroxide ions are called weak bases. E.g.
NH4OH(aq) ---------------- NH4+(aq) + OH- (aq)
Ca(Oh)2(aq) -------------- Ca2+(aq) + 2OH-(aq)
1)
2)
3)
4)
Mg(OH)2(aq)------------ Mg2+(aq) +2OH-(aq)
USES OF SOME COMMON BASES:
SODIUM HYDROXIDE(Naoh): Is used in the manufacture of soaps, artificial fibres
like rayon and in paper industry.
Potassium Hydroxide (KOH): is used in the manufacture of soft soaps, in nickeliron storage battery and for absorbing CO2.
Calcium Hydroxide [Mg(Oh)2] is used as an anti acid to neutralize acid in the
stomach.
Ammonium hydroxide (NH4OH): is used for removing grease from clothes in dry
cleaning and in cleansin window panes.
TESTS TO DISTINGUISH BETWEEN ACIDS AND BASES:
There are many substances which show one colour(or odour) in the acidic medium and
adifferent colour (or odour) in the basic medium. Such substances are called as acid- base
indicators.
There are two types of indicators:
1) Indicators showing different colours in acidic & basic medium:
e.g litmus solution, phenopthalein, methyl orange etc
* Acids turn blue litmus red. Bases turn red litmus blue.
* Phenopthalein is colourless in acidic medium and has pink colour in basic
medium.
* Methyl orange has red colour in acidic medium and yellow colour in basic
medium.3
2) Indicators giving different odours in acidic and basic medium(called olfactory
indicators):
e.g., onions, vanilla assence, clove oil etc
* Greater the amount of H+ ion produced in solution, strong is the acid- STRONG
ACID AND VICE Versa (small amount –weak acid).
* Greater the amount of OH- ion produced in solution, strong in the baseSTRONG BASE.
(small amount-weak base)
PH AND PH SCALE: (EXPRESSION ACIDITY OR ALKALINITY OF A COLUTION
IN TERMS OF PH_):
It is foun that in water or any beutral solution (i.e. which is neither acidic nor basic), the
H+ ion concentration & OH- ion concentration are equal. At 25°c, each of thess
concentration is equal to 10-7 mole per litre i.e in water or any neutral solution at 25°c.
Concentration of H+ ions = concentration of OH- ions =10-7 mole per litre further, it is
found that for any solution (neutral, acidic or basic), the product of H+ ion concentration
and OH- ion concentration (in mole per litre) is always constant and equal to 10-14 at 25°c.
this is called as ionic product of water. It is usuallu represented by the symbol KW. Thus,
Ionic product of water (KW)= concentration of H+ ions in mol L-1 x concentration of OHions in mole L-1
={H+} {OH-} = 10-14 at 25°c.
Thus, for a solution, if H+ ion concentration is known, OH- ion concentration is
automatically fixed (because ther product is always constant). Hence, we express the
acidic, basic or neutral character or any solution by simply expressing its H+ ion
concentration.
Sorensen, a Danish bio chemist, in 1909 sugessted a method of expressing molar
concentration of H+ ion in terms of PH which in Danish language stands for POTENZ de
hydrogen (means power of H+ ions). Thus, ph is defined as,
“PH of a solution is the magnitude of the negative power to which 10 must be raised to
express the hy6drogen ions concentration of the solution is moles per litre”
Or
The term “PH” is defined as the negative logarithm of the hydrogen ion concentration of
a given solution. The concentration be expressed as moles per litre.
Mathematically,
PH= - log (H+)
CLASS 10TH
SUBLECT ; PHYSICS
Electricity
Electricity is probably the eighth wonder of modern civilized world. Its utility &
discovery have revolutionized the homes & industries of the civilized world. Life
today is totally dependent on it.
The word Electricity is derived from a Greek word ‘Electron’ which means ‘Amber’
(a piece of Resin). Electricity is one of the forms of energy & it can be produced
from other types of energy such as energy of chemical reaction or of a mechanical
rotation of a dynamo.
In the 6th century B.C., a Greek Philosopher ‘Thales’ found that when “amber” is
rubbed with fur, it adds a remarkable property of attracting small pieces like dust,
leaves etc. This phenomenon is also noticed when a comb or scale or a barrel of pen
is rubbed on hair. Thus, a substance which exhibits this effect is said to be charged
or electrified.
ELECTRIC CHARGE & ITS PROPERTIES:
Charge, like mass, is a fundamental property of matter. There are two types of
charges- positive charge and the negative charge. Further, Charge carried by a
proton is positive & that carried by an electron is negative. A body gets positively
charged if it loses electrons & negatively charged if it gains electrons.
For example, When a glass rod is rubbed with silk, it loses electrons & becomes
positively charged and silk on other hand gains equal number of electrons and
becomes negatively charged i.e. electrons are transferred from glass to silk on
rubbing.
Some of the properties of electric charge include:
1) Unlike (i.e. opposite) charges attract each other and like (i.e. similar) charges
repel.
2) Electric charge is conserved i.e. it can neither be created nor destroyed..
3) Electric charge is additive i.e. total charge is the algebraic sum of individual
charges.
4)The force of interaction between any 2 point charges is directly proportional to
the product of the charges and inversely proportional to the square of the distance
between them, i.e.
F x q1q2/r2, or, F = K q1q2/r2------------------(1)
Equation (1) is the mathematical statement of Coulomb’s law, where ‘K’ is the
constant of proportionality, F is the magnitude of electric force, q1 & q2 are the unit
charges
S.I UNIT OF ELECTRIC CHARGE:
The S.I unit of electric charge is Coulomb which is denoted by the letter ‘C’.
1 Coulomb is that quantity of electric charge which exerts a force of 9 x 109 Newtons
on an equal charge placed at a distance of 1 metre from it.
A proton possesses a positive charge of 1.6 x 10-19c where as an electron possesses a
negative charge of
1.6 x 10-19c.
IC charge= 6.25 x 1018 electrons.
CONDUCTORS:
The substances which easily allow the flow of electric charge through them are
called conductors or those substances through which electricity can flow are called
conductors.
Examples:
All the metals like silver (best conductor), copper, Aluminum, Iron, Mercury etc are
conductors. Human body is fairly a good conductor. Aqueous solution of salts, acids
& bases are also examples of conductors.
Insulators:
The substances which don’t allow the flow of electric charge through them are
called Insulators or those substances through which electricity can’t flow are called
Insulators.
Examples:
Glass, Rubber, paper, dry wood, cotton, etc are the examples of Insulators.
Note: *The presence of ‘free electrons’ in a substance makes it a conductor.*
DI-ELECTRICS:
Dielectric is a substances which transmit electric effect without conducting. In other
words, a Di- electric is a substance that doesn’t conduct electric current through it.
However, when a piece of Di-electric is placed in an external electric field, indized
charges appear on the surface of di-electric. Hence di-electrics are the substances
which transmit electric effects without converting.
ELECTRIC CURRENT:
An electric current is defined as the ordered motion of electric charges.
Quantitavety, Electric current is defined as the rate of flow of electric charge i.e.
electric current is the quantity of charge flowing per unit time.
If a charge (Q) flows through a conductor in a time (T), then current (I) flowing
through the conductor is given as
I = Q/T, or Q = It
UNIT:
The S.I unit of current is called Ampere(A) in the honour of French Scientist ,
Andre-Marie Ampere (1775-1836).
1 Ampere = 1 Coloumb/1 Second
Or, 1A = 1c/s
Thus, the current flowing through a conductor is said to be 1 Ampere if 1 coloumb
of charge flows through it in 1 second.
Current is measured by an instrument Called Ammeter
Fig shows: Ammeter conducted in series with a conductor BC to measure the
current passing through it.
ELECTRIC FIELD:
The electric field is a space surrounding a charge or a system of charges within
which its influence can be felt.
Practically this field is limited upto a small distance beyond which the
electric force is not applicable.
ELECTRIC DIPOLE:
A pair of equal and opposite charges separated by a vector distance (a) is called an
electric dipole.
ELECTRIC POTENTIAL:
The electric potential (or potential) at a point in an electric field is defined as the
amount of work done in moving a unit positive charge from infinity to that point.
Electric potential is denoted by the symbol ‘V’ & its unit is volt.
POTENTIAL DIFFERENCE OR ELECTRIC POTENTIAL DIFFERENCE:
Potential difference two points A & B on a conductor through which a current is
flowing is defined as the amount of work done to move a unit charge from A to B.
OR
Potential difference between two points in an electric current is defined as the
amount of work done in moving a unit change from one point to another point
i.e., potential difference = work done/ quantity of charge moved.
i.e. potential difference, V= W/Q
where w = work done & q = quantity of charge moved.
The S.I unit of potential difference is ‘volt’ which is denoted by letter ‘v’. The
potential difference is also sometimes written in symbols as P.d.
The potential difference is measured by means of an instrument called volt meter. A
volt meter has high resistance.
NUMERICAL:
How much work is done in moving a charge of 2 coloumbs from a point of 118 volts
to a point at 128 volts?
We know that,
Potential difference = work done/ charge moved
Or, V=W/Q-------(1)
Here, V= 128-118
=10 volts
Work done, W=?
Charge=2 coloumbs.
Putting these values in Equation (1), we get
10=W/2
Or, W=10 x 2
Thus, work done, W=20 joules
ELECTRIC CIRCUIT & ITS COMPOSITION:
Electric lamps,heater , Ac and motors and various other devices which work on
electricity are called ‘loads’ because these consume electric energy.
A source of electric power (a battery or an ac source ) loads and switches and other
elements connected together by wires from ‘electric circuit’
A drawing showing the way the electric devices are conducted in a circuit is called
‘circuit daigram’or a ‘schematic diagram’. In these diagrams, certain symbols are
used to represent various devices and some of these are shown below
A connecting wire is usually made of copper covered with cotton or plastic
insulation.
A ‘battery’ is a combination of two or more cells. A thin long line represents the
positive terminal of the cell where as a short thick line represents the negative
terminal of cell.
A ‘ Resistar’ provides a constant resistance in electric circuit. A ‘Galvanmeter’ is a
device used for detecting yhe flow of current in an electric circuit. It has no
positive(+) or negative (-) terminal marks on it.
An ‘Ammeter’ is a device used for measuring current. It has +ve & -ve marks on its
terminals.
A ‘voltmeter’ is a device used for measuring potential difference between two
points in an electric circuit.
A ‘closed electric circuit’ is one in which the key is closed and current flows
continuously.
An ‘open electric circuit is one in which the key is open and there is no flow of
current.
A schematic diagram of an electric circuit consisting a cell, electric bulb, a plug
key, ammeter & volt meter is shown below
*Rheostat is used to change resistance in an electric circuit.
OHM’S LAW:
George Ohm (1781-1854) was the first to make a quantitative study about the
relationship between current and potential difference. He put forth a law known
after his name as Ohm’s law.
Ohm’s law give a relationship between current and potential difference. According
to Ohm’s law, “At costant temperature, the current flowing through a conductor is
directly proportional to the potential difference across its ends.”
If ‘I’ is the current flowing through a conductor and ‘V’ is the potential difference
(or voltage) across its ends, then according to Ohm’s law:
I x V(At constant temperature)
This can be also written as
VxI
V=RxI
Where ‘R’ is a constant called resistance of a conductor. The value of this constant
depends upon the nature, length, area of cross section & temperature of the
conductor. The above equation can also be written as
V/I = R-----------(1)
Where V = Potential difference, I= current R= resistance
The equation (1) is a mathematical expression of Ohm’s law.
EXPERIMENTAL VERIFICATION OF OHM’S LAW:
To experimentally verify Ohm’s law, an electric circuit as shown in figure is set up
which contains the flowing components:
1)
2)
3)
4)
A battery which is used to send current in the circuit.
A rheostat (RH) which is used to change and adjust current in circuit.
A resistance wire AB of fixed resistance R.
An ammeter (A) which is used to mrasure current in the circuit passing through
A is the same as that passing through R.
5) A voltmeter (V) is connected in parallel across R to measure potential
difference between points A & B of resistance wire.
6) A plug key (K) is used to open or close the circuit as and when required.
When the key ‘K’ is closed, a current starts flowing in the circuit. The current in
circuit is changed by adjusting the rheostat and the readings of V & A are taken.
These readings give us the value of Pd (V) across R and Current (I) flowing
through it.
It is found that V/I is practically constant, i.e.
V/I = constant, or V x I
This verifies Ohm’s law.
RESISTANCE:
The property of a conductor due to which it opposes the flow of current through
it is called resistance.
The resistance of a conductor is numerically equal to the ratio of potential
difference across its ends to the current flowing through it, i.e.
Resistance= Potential Difference/current
Or, R = V/I
The S.I unit of resistance is Ohm which is denoted by symbol Omega Ω.
1 Ohm is the resistance of a conductor such that when a potential difference of
1 volt is applied to its ends, a current of 1 ampere flows through it.
NUMERICAL:
Potential difference between two points of wire carrying 2 ampere current is
0.1 volt. Calculate the resistance between these points.
Sol: From Ohm’s Law,we have
V/I = R
Here, V = 0.1 volt, I = 2 Ampere, R= ?
Putting these values in above equation
0.1/2=R
0.05= R
Or, R = 0.05Ohm(or 0.05 Ω)
FACTORS AFFECTING THE RESISTANCE OF A CONDUCTOR:
The resistance of a conductor (or wire) depends upon the flowing factors
1) Effect of length of conductor: It has been found by experiments that on
increasing the length of wire, its resistance increases and on decreasing the
length of wire, the resistance decreases. Actually resistance of a conductor is
directly proportional to its length, i.e.
Resistance x L
2) Effect of area of cross section of conductors: It has been found
experimentally that the resistance of a conductor is inversely proportional
to its area of cross section. That is,
Resistance, R x I/A (where A is the area of cross section of
conductor)
Since, the resistance of wire is inversely proportional to its area of cross
section, therefore when the area of cross section of wire is doubled, its
resistance gets halved and vice-versa.
3) Effect of nature of material of conductor: The resistance of a conductor ( say
wire) depends on the nature of material of which it is made. Some materials
have low resistance whereas others have high resistance.
4) Effect of Temperature: It has been found that the resistance of all the pure
metals increases on raising the temperature and decreases on lowering the
temperature. But the resistance of alloys like nichrome, constantan etc is
almost unaffected by temperature.
RESISTIVITY:
Resistivity of a substance is numerically equal to the resistance of a rod of that
substance which is 1 metre long & a square metre in cross section.
The S.I unit of resistivity is Ohm metre.
OR
Resistivity of a material of a conduvtor is defined as the resistance offered by
the conductor whose length is 1m and cross sectional area is 1m 2.
CAUSE OF RESISTANCE IN A CONDUCTOR:
When a potential difference is applied across a conductor the free electrons in
it move a certain velocity called ‘drift Velocity’. But during motion, electrons
frequently collide with Kernals as they move through the conductor. These
collusions slow down the speed of electorns. Therefore, larger the numbers of
collusions, the larger is the resistance of material.
COMBINATION OF RESISTANCES OR RESISTORS
The resistors can be combined in two ways
1. In series
2. In parallels
If we want to increase the total resistance, then the individual resistances are
connected in series and if we want to decrease the resistance, then the
individual resistances are connected in parallel
1. Resistance in series:
When several conductors are connected end to end so that same current
passes through them, the conductors are said to be in series.
Or
A number of resistors are said to be connected in series if these are joined
end to end and the same (I.e total) current flows through each on t of them
when a potential difference is applied across the combination.
Let R1, R2 and R3 be the resistances of these conductors and V be the
potential difference across the conductors so that
V = V1 + V2 + V3 _________ (I)
Now by Ohm’s law
V = IR, i.e. V1 = IR1, V2 = IR2, V3 = IR3
Therefore equaltion (I) becomes
IR = IR1 + IR2 + IR3
Or R = R1 + R2 + R3
Thus the total resistance of a circuit is equal to the sum of the resistances
of the individual conductors joined in series
2. Resistance (or Resistors) in parallel
When several conductors are connected such that one end of all them is at
one point and others are at other point so that different currents pass
through them.
Or
Resistors are said to be connected in parallel, if the potential difference
across each of them is same and equal to applied potential difference
Or
A number of resistors are said to be connected in parallel if one end of each
resistor is connected to one point and the other end is connected to
another point so that the potential difference across each resistor is the
same and is equal to the applied potential difference between the two
points
Let R1 , R2 and R3 be the resistances of conductors and I1, I2 and I3 are the
currents through them so that
I = I1+ I2 + I3
(i)
Now applying ohm’s law equation becomes
V/R = V/R1 + V/R2 + V/R3
Or 1/R = 1/R1 + 1/R2 + 1/R3
Thus when a number of resistances are connected in parallel, the reciprocal
of the comvined resistances is equal to the sum of the reciprocal of
individual resistances.
Heating effect of current
Whenever a current is passed through a conductor, it becomes hot after
sometime,. This means that electric energy is being converted into heat
energy. This effect is known as heating effect of current or the Joule’s
heating.
Electric bulb, electric iron, electric heater etc are some of the appliances
which are based on this effect.
In 1841, James Prescott Joule (1818 – 1889) experimentally studied the
heating effect of an electric current. He gave a law known as Joule’s law of
heating.
It states, “ the amount of heat produced (H) in a conductor due to the flow
of current though it is proportional to the square of the current, the
resistance of the conductor and the time for which current flows.”
H α I2Rt ------- (i)
Where ‘H’ is the amount of heat produced, ‘I’ is the current ‘R’ is resistance
and ‘t’ is time
Equation (i) is the mathematical expression of Joule’s law.
When a potential difference is applied across the conductors the free
electrons inside it get drifted towards one end of the conductor. But during
the course of their motion, these electrons collide with the Kernels and
transfer their energy to them. As a result the average kinetic energy of the
vibration of the atoms of the conductor increases resulting in the
production of heat in the conductor. Thus loss in potential energy of the
electrons due to the applied potential difference appears as heat energy in
the conductor. This heat is often called as Joule’s heat.
ELECTRICAL ENERGY:
The total work done by a current in an electric circuit is called electric
energy.
The S.I. unit of electrical energy is watt hour.
ELECTRIC POWER:
It is defined as the “rate at which work is done by an electric current”
Or
It may be defined as the rate at which electrical energy is being converted
into heat energy.
i.e. Power =work done/Time taken
or P= W/t
The S.I. unit of electrical power is ‘watt’ which is denoted by letter w.
Watt = 1 Joule/1 seconds (1 watt= 1 volt x 1 ampere =1J/1C x 1C/1S
Therefore, 1w= 1J/1S).
SUPER CONDUCTORS:
In 1911, Dutch Physicist, Heike Kammer lingh ones (1853-1926) discovered
the resistivity of mercury reduced to zero at 4.2k.
Many metals and even poor conductors such as lead have been found
to have very low resistivity at low temperature. This property is called super
conductivity while materials under such conditions are called super
conductors. The temperature below which a material is in super conducting
state is called transition temperature or critical temperature.
Super conductors are the materials which have zero resistance at a
particular temperature called critical temperature e.g. Mercury at 4.2K,
copper at 40K etc.
Since super conductor have zero resistance, these can be used for
transmission of electric power without loss of energy.
end of each resistor is connected to one point and the other end is
connected to another point so that the potential difference across each
resistor is the same and is equal to the applied potential difference
between the two points
Let R1 , R2 and R3 be the resistances of conductors and I1, I2 and I3 are the
currents through them so that
I = I1+ I2 + I3
(i)
Now applying ohm’s law equation becomes
V/R = V/R1 + V/R2 + V/R3
Or 1/R = 1/R1 + 1/R2 + 1/R3
Thus when a number of resistances are connected in parallel, the reciprocal
of the comvined resistances is equal to the sum of the reciprocal of
individual resistances.
Heating effect of current
Whenever a current is passed through a conductor, it becomes hot after
sometime,. This means that electric energy is being converted into heat
energy. This effect is known as heating effect of current or the Joule’s
heating.
Electric bulb, electric iron, electric heater etc are some of the appliances
which are based on this effect.
In 1841, James Prescott Joule (1818 – 1889) experimentally studied the
heating effect of an electric current. He gave a law known as Joule’s law of
heating.
It states, “ the amount of heat produced (H) in a conductor due to the flow
of current though it is proportional to the square of the current, the
resistance of the conductor and the time for which current flows.”
H α I2Rt ------- (i)
Where ‘H’ is the amount of heat produced, ‘I’ is the current ‘R’ is resistance
and ‘t’ is time
Equation (i) is the mathematical expression of Joule’s law.
When a potential difference is applied across the conductors the free
electrons inside it get drifted towards one end of the conductor. But during
the course of their motion, these electrons collide with the Kernels and
transfer their energy to them. As a result the average kinetic energy of the
vibration of the atoms of the conductor increases resulting in the
production of heat in the conductor. Thus loss in potential energy of the
electrons due to the applied potential difference appears as heat energy in
the conductor. This heat is often called as Joule’s heat.
ELECTRICAL ENERGY:
The total work done by a current in an electric circuit is called electric
energy.
The S.I. unit of electrical energy is watt hour.
ELECTRIC POWER:
It is defined as the “rate at which work is done by an electric current”
Or
It may be defined as the rate at which electrical energy is being converted
into heat energy.
i.e. Power =work done/Time taken
or P= W/t
The S.I. unit of electrical power is ‘watt’ which is denoted by letter w.
Watt = 1 Joule/1 seconds (1 watt= 1 volt x 1 ampere =1J/1C x 1C/1S
Therefore, 1w= 1J/1S).
SUPER CONDUCTORS:
In 1911, Dutch Physicist, Heike Kammer lingh ones (1853-1926) discovered
the resistivity of mercury reduced to zero at 4.2k.
Many metals and even poor conductors such as lead have been found
to have very low resistivity at low temperature. This property is called super
conductivity while materials under such conditions are called super
conductors. The temperature below which a material is in super conducting
state is called transition temperature or critical temperature.
Super conductors are the materials which have zero resistance at a
particular temperature called critical temperature e.g. Mercury at 4.2K,
copper at 40K etc.
Since super conductor have zero resistance, these can be used for
transmission of electric power without loss of energy.
CLASS 10 TH
SUBJECT MATHS
TOPIC; PROBABILITY (to be done at home on loose sheets)
SUBJECT : URDU
CLASS: 10TH
WRITE NOTES ON
1. MOHAMMAD HUSSAIN AZAD
2. YASEEN BEIGH
3. IQBAL