Download ATOM, ELECTRICITY AND MAGNETISM

Radio serial-100 Year of atom…….
ATOM, ELECTRICITY AND MAGNETISM
Research and Script –Dr- Arvind Dubey
(Signature tune..…………………………………...........................................................................Fades out)
(Title song………………………………………………………………………………………………………………….Fades out)
(Opening music……………………………………………………………………………………………………………Fades out)
Atom-
I am atom. Since the inception of this radio serial “100 years of the atom”, we
have come long way together. In last episode you listened……….. (Recap of last
episode). Electricity has become the basic necessity of every household be it
villages, towns or cities. All the industrial progress of any nations can be directly
translated in terms of availability of electric power. Today electricity has
influenced every aspect of our life. Do you know who is behind this electricity?
Who is behind its production, transmission and utilization? Engineers, no…
scientists, no, workers no. Really it’s me…yours sincerely, the atom with all its
subatomic particles, especially my mischievous little one……the electron. So we
endorse today’s episode in the name of my lovely electron…..
(Change over Music)
Scence-1
Place-
A room in Romi’s house.
Time-
Evening
(Divya is studying in her room, Romi enters)
(Opening music……………………………………………………………………………………………………………Fades out)
Romi-
Divya di , Divya di, what are you doing?
Divya-
Tomi……I mean Romi my beloved brother, I know you have low I.Q…..ok, but you
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are a little blind too. Don’t you see am studying?
Divya- Diva di why are you always behind me? I too deserve some respect and dignity. OK now
I will not tell you what I came to tell you.
Divya-
So you were going to tell me something, then shoot……
Romi-
No……no no way.
Divya-
Please, my sweet little brother, please.
Romi-
I was about to show you some magic.
Divya-
Magic? So you again started doing the same nonsense. How many times I told
you that there is nothing like magic.
Romi-
Then?
Divya-
These are some science experiments which are so shrewdly and cleverly
performed.
Romi-
Ok……Ok…on more lecturing…….are you interested in listening?
Divya-
Ok shoot……
Romi-
Look Divya di……this is my pen… an ordinary pen…..you can look at it.
Divya-
Ok.
Romi-
Now I am rubbing it on my woolen sweater…. this way….now see it has started
attracting, dust, small pieces of paper…...
(Divya starts laughing loudly)
Romi-
What is so humorous in it. Why are you laughing Divya di?
Divya-
Magic, vow…what a magic………really great.
Romi(Irritated)-…why..It’s not fair Divya Di, it’s not fair.
Divya-
Ancient Greeks knew your magic very well, centuries back.
Romi-
Was it so?
Divya-
Yes my dear brother Romi Ancient Greeks that amber behaved oddly, like
attracting feathers collecting dust particles- when rubbed by fur of other objects.
Romi-
Amber what was that Divya di?
Divya-
Romi Amber is very pretty golden brown stone that sparkles orange and yellow
in sunlight. Actually it is fossilized tree sap.
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Romi-
So ancient Greeks knew it?
Divya-
Of course but they did not know that what it was, that caused this behavior.
They didn’t know that they had discovered first example of static electricity.
Romi-
Electricity, you mean the strange phenomenon which I have showed you is
electricity?
Divya-
Yes Romi, yes……Electron, Electricity, and Electronics all originate from a Greek
word “Elektor” means beaming sum.
Romi-
But this word electricity…….?
Divya-
The Latin word Electricus which means “produced from amber by friction,”
Became “Electricity” in English language.
Romi-
So this was considered a magic in those days too?
Divya-
Not exactly, but a strange phenomenon.
Romi-
Then?
Divya-
Nobody paid much attention to this until about 1600 AD, when Dr. William
Gilbert studied this phenomenon scientifically.
Romi-
Then….?
Divya-
He said that many objects can be made to behave in this manner. Amber
acquired, what he called resinous electricity when rubbed with fur.
Romi-
……and the other one?
Divya-
Yes, when glass is rubbed with silk, it acquired vitreous electricity, he concluded.
Romi-
Strange.
Divya-
Many strange ideas came later on to explain this phenomenon even by then
notable scientists.
Romi-
How…?
Divya-
as they did not know about electron and proton so they thought electricity is a
result of invisible fluid exchange between two materials.
Romi-
Ridiculous.
Divya-
It took centuries when truth was finally realized.
Romi-
What truth?
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Divya-
That it is due to exchange of electrons between two rubbing objects.
Romi-
Electrons, how come electrons are related to electricity?
Divya-
Related to Electricity, The electricity is nothing but exchange of electrons.
Romi-
Really?
Divya-
Romi, we bought some balloons on your birthday. I think all were not used.
Romi-
Yes I have many.
Divya-
Then bring some of them …….?
Romi-
why?
Divya-
I will show you some magic…..Divya Mathur’s show……….Abra ka
Dabra……….Gili…. Gili…..Gili”
(Change over Music)
Scene-2
Place & time- Same as that of scene-1
(Opening music……………………………………………………………………………………………………………Fades out)
(In this Divya and Romi will speak in magician and his helper boy’s or jamure’s tone)
Divya-
Romi.
Romi-
Yes Divya di
Divya-
Have you blown up all the balloons?
Romi-
Yes.
Divya-
And tied their mouth with thread, tightly?
Romi-
Yes tightly………Divya di, come on, finish this suspense and let the cat out of the
cage.
Divya-
Ok , so here comes Divya Mathur’s physics show. Come here, Romi brother.
Romi-
OK.
Divya-
rub one balloon on your sweater (Noise of rubbing the balloon)…….yes vigorously
(Footstep noise)
yes.
Romi-
OK.
Divya-
Now Romi sir, touch this balloon to the front wall……….yes……now leave it
there….don’t afraid, it will not fall.
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Romi-
Vow, it has sticked to the wall, without gum or tape…… sheer magic Divya di.
Divya-
Romi ji.
Romi-
Yes, Divya Mathur ji.
Divya-
you are a damn fool.
Romi-
Yes……….no………no…..why?
Divya-
because I already told you, there is nothing like magic these are--------------
Romi (interrupting)-………science experiments, so cleverly done to hide the actual process.
Divya-
Yes.
Romi-
Then what are the facts?
Divya-
Before that, next item of today’s show.
Romi-
what?
Divya-
Rub that pair of balloons, tied together, on your sweater again.
Romi-
ok ………rubbing.
Divya-
Now suspend them by the common thread…..o…o ……..where …………..where……
(Noise of rubbing)
Ok…….on that hook.
Romi-
OK but these are moving apart from each other, why? Divya Mathur Ji ?
divya-
Hove patience brother and cool down.
(Change over music)
Scene-3
Place-
As that of Scene-1
Time-
As that of Scene-1
(Opening music……………………………………………………………………………………………………………Fades out)
(Divya and Romi are talking)
Romi-
Divya di your physics show has come to end but you didn’t tell that why it
Happened?
Divya-
Do you know the last orbit of any atom is called Valence orbit
Romi-
Valence orbit?
Divya-
When the valence orbit of an atom is fully saturated or having enough electrons
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in it, is called stable orbit.
Romi-
Stable means strong orbit?
Divya-
For purpose of understanding it’s OK. In some atoms, valance orbit are not
having enough electrons…..
Romi-
Means weaker orbit, from which electrons can easily be knocked out.
Divya-
You are right Romi ji.
Romi-
But Divya Mathur B.Sc. ji, would you explain why these balloons repelled each
other?
Divya-
When you rub the balloon, it picks up extra electrons from your sweater and
becomes slightly negatively charged. These negatively charged balloons are
attracted to the positively charged wall.
Romi-
And this is how the balloons stick over the wall. What is about those twin
balloons tied together by a single thread and hanged on the hook which repelled
each other?
Divya-
Those two balloons, hanging over the wall, were both negatively charged, same
type of charges repel each other so these balloons did the same.
Romi-
In rainy season at times there is thunder and lightning in the clouds, people call
it “Falling of electricity”.
Divya-
This is really a form of static electricity.
Romi-
Really?
Divya-
Yes, clouds become negatively charged as crystal inside the clouds rub against
each other, while on the ground positive charge increases.
Romi-
But how does this lightening occur?
Divya-
In this process clouds get so highly charged that the electrons jump from the
ground to the cloud or from one cloud to another cloud.
Romi-
Ok, So this causes that huge spark which we call lightening.
Divya-
Exactly, it can destroy buildings, kill animals and people; whosever come in its
way. So lightening protectors are installed over tall buildings.
Romi-
Lightening protectors, what is that?
6
Divya-
It is a copper strip long enough to reach form top of the building to down up to
the earth. It’s upper and is pointed. When lightning strikes the building, the huge
charge travels through this metal strip, directly to earths. This saves the building.
Romi-
Why?
Divya-
Because copper is good conductor of electricity so this static electricity travels
very fast to ground.
Romi-
Good conductor, what is good conductor of electricity?
Divya-
Some materials have few loosely held electrons which moves through these
materials very easily, hence charge faces least resistance in traveling through
them.
Romi-
These are called good conductors of electricity, aren’t these?
Divya-
Yes Romi, good conductor of electricity or simply conductors, such as Copper,
Aluminium and almost all the metals.
Romi-
And the materials, through which electricity does not pass easily or not at all, are
called bad conductors of electricity.
Divya-
Yes, these are commonly called Insulators.
Romi-
Why are some materials insulators?
Divya-
Because these materials hold their electrons tightly hence electrons do not move
through them, examples are- dry cloth, glass, dry air etcetera.
Romi-
It means these insulators are useless for electricity.
Divya-
No Romi , rather these insulator make use of electricity safe and convenient.
Romi-
How?
Divya-
Have you seen wires used in electric wiring?
Romi-
Yes, in these copper or Aluminum wires are surrounded by rubber of plastic
covering.
Divya-
As the outer- covering of these wires is made up of insulators like plastic or
Rubber, the chances of getting shock on touching the wire are almost negligible,
even when the electricity is flowing through inner copper wire.
Romi-
Divya di you are using a new word resistance. My physics teacher too very often
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uses it. What does it mean?
Divya-
Practically resistance means obstacle but here it shows how well a conductor or
metal conducts electricity through it.
Romi-
What?
Divya-
Lower the resistance of a substance the better it conducts electricity. Thinner the
wire is, bigger the resistance will be.
Romi-
So the high resistance substances are useless in electricity conduction or flow,
divya di.
Divya-
Certainly not, take the example of heater coil of light bulb. The wires used in
these are of high resistance.
Romi-
So electricity will not pass easily though them.
Divya-
Romi, do you know what the flowing of electricity or electric current is ment?
Romi-
Little bit.
Divya-
Once you apply voltage on one side of wire, it charges electron in the outer
most valiancy orbits of atoms and few electrons are knocked off from these
valence orbit.
Romi-
free electrons?
Divya-
Yes these electrons travel in a conductor to a very small distance and hits the
electron of nearby atom which are knocked off. This cycle goes on and this way
electron transfer negative charge from end to another end of the wire.
Romi-
Divya di, so electrons move from one end of the wire to other end of wire.
Divya-
Not from one end of wire but from negative pole of the battery to positive pole
…… romi picks up that torch ………Yes……. (sound effect)…… now open it and take
the battery out …..yes now look at this battery .
Romi-
At one end of it is a metal cap.
Divya-
This in the positive pole of the battery.
Romi-
Positive pole Ok. A positive mark too is printed on the covering of Battery …….
here.
Divya-
And the flat end down is negative pole. If we connect these two poles via a
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conductor wire, it make a circuit.
Romi-
So electrons flow in this circuit, Divya di.
Divya-
Yes Romi, the electrons move from negative pole, from where they are in excess
to positive pole where they are less.
Romi-
So the electric current too?
Divya-
No Romi , electric current is supposed to flow from positive pole to negative
pole.
Romi-
when the circuit is completed the electrons begin moving quickly depending
upon the resistance of the circuit. They try to get across as fast as to destroy the
circuit.
Divya-
Then what we can do to save the circuit?
Romi-
We can resist the movement of electrons by making electricity to do the work
during flow in the circuit.
Romi-
Let the electricity to do the work during its flow, what does it mean?
Divya-
We can make the electricity flow the resistance of the filament of a bulb of
resistance of room heater.
Romi-
Ok so in getting the bulb glow or room heater’s filament hot, electricity faces
resistance and does some work.
Divya-
And this way limits the flow of electrons through the circuit and saves the circuit.
Romi-
Ok so this way resistance is important in the circuit?
Divya-
Yes whatever work we get from electricity is due to resistance that falls in the
way of its flow.
(Ma calls from distance)
Ma-
Romi where are you. I saw you entering the house but eloped thereafter. Where
are you?
Romi (Answering from distance)Ma-
I am here in Divya di’s room.
Oh so you again started disturbing her. You know she is having exams next
month. (Voice comes nearer) like to have some snacks?
Romi-
Yes Ma yes, certainly if it is pakaura.
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Ma-
Pakauras….. pakauras……. Pakauras…….pakauras every day. Well I will make
some for you. Divya would you like to have some?
Divya-
Certainly ma, provided this demon spares few for me……oh electricity is gone.
Romi-
Look Divya di you called me demon and electricity is gone so beware…..
Divya-
God knows how long it will take too come back.
Romi-
Very long time, because it is coming on foot ….poor electricity.
Divya-
Nonsense, this movement is so fast you can’t even notice it, you push the button
and the bulb glows.
Romi-
Is it same the electricity which comes in our house?
Divya-
Exactly but the electricity produced in the battery is different from that which
comes in our house.
Romi-
How?
Divya-
In battery the positive and negative poles are fixed so current flows in one
Direction only
Romi-
From positive pole to negative pole?
Divya-
Yes so this current is called direct current or D.C.
Romi-
Direct current or D.C. and what about the current comes in our houses?
Divya-
That is Alternating current or A.C.
Romi-
Why alternating current?
Divya-
Because in this negative and positive pole change into each other, hundred time
per second.
Romi-
Means the direction of electricity also change in the circuit, hundred times per
second.
Divya-
Exactly, that’s why this current is called alternating current or A.C.
(Papa enters)
Papa (Entering)- Oho smell of Pakauras……oho Divya……Romi, you both are savoring pakauras.
Divya-
You are well in time papa, have pakauras and thank mummy.
Papa-
Of course, of course, first let me refresh and wash myself, what about you;
sharing only pakaura or something else.
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Divya (Laughing)- Papa today this Romi come to show me magic but go into thick soup and had
to tolerate full lecture on electricity.
Papa-
Ch…ch….ch….it is not fair Divya you forced to learn something to a person who is
allergic to studies. By the way Romi what you were forced to listen by Divya.
Romi-
Nothing much Papa, she told me something about electricity and that electrically
the substance are of two types- conductors and insulators.
Papa-
For all practical purposes this much is Ok.
Romi-
Otherwise Papa?
Papa-
Otherwise electrically all the substance are of 4 types.
Divya & Romi (Simultaneously) - 4 types?
Papa-
Yes conductors, Insulators and besides these two there are semiconductors and
super conductors.
Romi-
Semiconductors and superconductors.
Divya-
Romi don’t worry these two are not for you, well above you level.
Romi-
Divya di, don’t underestimate me. What do you think, I am not worth it? Don’t
challenge me.
Divya-
Oho.
Papa-
Don’t fight……don’t fight, ne too an intelligent gay.
Romi-
and today, I will learn what are these semi and superconductors?
Papa-
Ok….Ok ask your Ma to bring my share of Pakaura’s in my room after a while.
(Papa leaves)
Romi-
I requested Papa in the morning to bring some thing for me. Let me see, it he has
brought it.
(Romi leaves)
Divya-
Huh, Papa’s CHMACHA
(Change over music)
Secne-4
Place-
Papa’s Room
Time-
Evening
11
(Opening music……………………………………………………………………………………………………………Fades out)
(papa and Romi are inside the room and taking)
Romi-
Papa, now tell me about semiconductors and superconductors.
Papa-
Why you are so interested in Semiconductors and Superconductors?
Romi-
I want to know more than Divya Di. She always teases me.
Papa-
You can’t, because she is in B.Sc. studying physic, me a professor in physics and
you a student of 9th class, how all of us can be equal?
Romi (Clearly irritated)-Papa please….tell me clearly, will you teach me semiconductors and
Superconductors or not? Otherwise I will search the internet.
Papa-
Ok…Ok semiconductors are the substances which are neither good conductor of
electricity nor the insulators.
Romi-
So these are the ones whose electrical conductivity falls between that of
Conductors and Insulators.
(Divya comes)
Divya-
Oho…..Papa, is Romi poisoning yours ears against me and you are listening…..
this is an not fair papa this is not fair.
Papa-
No…No no Divya my child nothing like that…..come…..come…. inside
Divya-
How can I? Romi is not letting me enter. Look he is covering in the whole door
with both of his arms.
Papa (In lond tone)- Romi…….no…nonsense…..let her come in…..leave the door……
Romi-(Irritated) Ok…..Ok….
Papa-
Ok… Romi-…….cool down so we were talking about Semiconductors……these are
the substances.
Divya-(Interrupting) Papa…..Semiconductors are like our Romi……
Romi-(Interrupted) Papa pleeeeeeease……. ask her to shut up.
Divya-
No papa, listen to me. Semiconductors behave same way this Romi is behaving.
Romi-
How, how I am behaving…..?
Divya-
Suppose I am electricity.
Romi-
Electricity….do you give shock
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Divya-
No…..No……I simply slap….want to get one?
Papa-
Romi listen to her, yes Divya….
Divya-
So if I am electric current then Romi was behaving like semiconductor. He did
not let me enter the room, when papa, you warmed him a bit, I mean scolded
him he let me enter the room, same way as semiconductors do…..
Papa-
Excellent….Brilliant explanation…..marvelous ….Divya. Did you understand Romi?
Romi-
Yes Papa Yes.
Papa-
There are some natural conductors such as Silica and Germanium. On room
temperatures these are nonconductor to electricity but when these are heated,
they start conducting electricity.
Romi-
Ok.
Papa-
There are substance which in pure are bad conductors of electricity but after
mixing a little amount of impurity they become conductors of electrons.
Divya-
Mixing of impurity, I think this process is called “doping”
Papa-
Yes Divya?
Romi-
But why this happens at all?
Papa-
After mixing some impurities in these substances, the number of electrons in
these substances increase.
Divya-
Because electrons are negatively charged so after doping the amount of negative
charge increases in these substances. So these semiconductors are called n-type
of semiconductors …..’n’ for “Negative”
Romi-
n-type semiconductors ….papa?
Papa-
Yes Romi, but in some substances after doping electrons are knocked out?
Divya-
After ejecting the electron leave an empty space.
Papa-
Because negative charge had ejected from this empty space so these spaces
become positively charged hence called “P-hole”…. “p” for “positive”.
Divya-
Because these substances contain number of p-holes, hence these
semiconductors are called p-type semiconductors.
Romi-
So there are two types of semiconductors; n-type and p-type.
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Papa-
But there is a strange phenomenon.
Romi-
What?
Papa-
Both p and n-type of semiconductors becomes good conductors of electricity but
when one p type semiconductor is joined with a n-type of semiconductor, this
joint does not allow any electricity to pass through it.
Divya-
This is called p-n junctions. isn’t this papa?
Papa-
Yes Divya and this combination of one p-type semiconductor with one n-type
semiconductor is called “Diode”.
Romi-
Diode?
Papa-
Yes Romi, in electronics these diodes act as micro valves, which allow only
unidirectional flow of current.
Divya-
Diodes are important components of many electronic equipment, aren’t these?
Papa-
Yes, they save these equipments from damage while connections of battery are
reversed.
Divya-
Some diodes emit light of different colours when electricity is passed through
them.
Papa-
Yes….Yes…..these diodes are called light emitting diode or L.E.D.
Romi-
Same LED which is used in festival lighting and many electrons equipments?
Divya-
Exactly.
Papa-
Divya if we sandwich a p-type semiconductors between two n-type
semiconductors or vice versa, do you know what will it be called?
Divya-
I think this sandwich will be called “Transistor” either n-p-n type of p-n-p type;
depending upon which type of conductor in on outer side.
Papa-
These transistors can be electronically printed on a microchip, so a smaller
microchip may accommodate thousand of transistors on it.
Papa-
It caused a marked decrease in the size of computers.
Divya-
Initially these computers were of the size small buildings. Which are now
reduced to the size of our desktops and Laptops.
14
Papa-
Semiconductors made this relentless progress of mobile, possible.
Divya-
The microchips contain several transistors and diodes on it. These are called
“Integrated circuits” or “ICs”. Electronic equipments contain one to several
hundred of these ICs.
Papa-
Besides these Semiconductors there are substances which offer almost no
resistance to the flow of electricity through them.
Divya-
Are you talking about superconductors, Papa?
Papa-
Absolutely right Divya, theoretically when current starts flowing in the loop of
these substances, it can flow indefinitely without losing its intensity and
strength.
Romi-
Really? Which substances behave as superconductors?
Papa-
Romi at the temperature of minus 135 to 270 degree centigrade, Mercuric
cuperate, a compound of Mercury, Thallium, Barium, Cadmium, Copper, Gold
and Indium, a compound called Niobium Nitride, an alloy of Gold and Indium
show superconductivity.
Romi-
On such low temperatures……my God how these can be used?
Divya-
These are very useful. Some unbelievable feats are achieved by superconductors.
Papa-
Yes Romi, very powerful electromagnets can be made from these
superconductors that are used in important diagnostic tools like MRI and
research gadgets like particle accelerators.
Divya-
In Maglev trains these superconductors are used to achieve levitation.
Romi-
Maglev trains, what are these?
Papa-
These are ultra super fast trains in which wheals bearings and axles are not used
for movement.
Romi-
What, then how do these trains Move?
Papa-
Maglev is a short form of “Magnetic levitation” which means to suspend an
object in air without any support and this is done by powerful superonducting
magnates.
15
Divya-
Maglev trains are suspended above its track in air and the thrust to move the
train is also provided by the magnet.
Papa-
As these trains made to float in the air well a above the track so there is no
friction between train and track. Hence these trains move very fast.
Divya-
Maximum speed achieved by these trains on Japanese tracks is up to incredible
581 Kilometers per Hour.
Romi-
Vow, we consider the trains with a maximum speed of 150 Kilometers per Hour
as super fast, so these trains can be called ultra-super fast.
Papa-
Not only this, There are other trains which can move with an unbelievable speed
of 6000 to 8000 Kilometers per hour.
Romi (Surprised) - 6000 to eight thousands kilometers per hour? What should we should call
These? Super-duper sonic trains or trains flying at very low altitude?
Papa-
These are called Vac-trains.
Divya-
Vac-trains?
Papa-
Yes Divya whatever resistance these wheel, bearing and axle less Maglev trains
face, is due to air resistance. So Maglev lines are used in airless or partially air
evaluated tunnels. Lack of air resistance along with lack of track friction, allow
these trains to achieve up to 5-6 times the speed of sound, surpassing the speed
of fastest supersonic plane.
Divya-
Where are these trains being operated?
Papa-
These are running now on experimental level in China but the technology can be
put in to general operation by the year 2020.
Divya-
Besides, these superconductors are also used in making frictionless bearings,
superconducting electric generators, superconducting energy storage and power
transmissions etcetera.
Papa-
The power of superconductors is not fully tapped but scientists are hopeful that
superconductors will certainly cause a big social change in the near future
(Ma enters and puts plate of pakauras over the table)
16
Ma-
Oho, so your class is in progress here too. Divya stop discussion and let your
papa have some snacks and rest.
(Change over music)
Atom-
So here I am, your good old friend Atom…………your co-traveler in this long
journey of 100 years of atom. Whatever you see, what so ever you do or feel, my
naughty little electrons make the basis of everything. You listened Divya, Romi
and their father talking of superconducting magnet. Who made it possible? My
electron. Even the magnetism too is due to my electron. You don’t believe me.
Ok, then listen what Romi and their papa is talking.
(Change over music)
Scene-5
Place-
Study of Divya
Time-
Morning
(Divya is studying, Romi enters the room)
Romi (Entering)-Divya Di, today is Sunday and you studying?
Divya-
I want to be a great scientist so I have to work hard……. Romi my dear brother
can you give me a pin from that pin box?
Romi-
Ok…. (Adequate sound effect) Look Divya Di even if I make this pin box upside
down, the pins do not fall. Rather they stick to the mouth of pin box.
Divya-
Because there a magnet ring on the mouth of pin box, which sticks pin to itself
hence they do not fall down.
Romi-
Magnet, why a substance becomes magnet?
Divya-
Due to electrons Divya Di, You said that electricity is due to electrons and now
you say that magnet too is due to electrons
(Papa enters)
Papa-
Yes Romi, Divya is right Electricity and magnet are two face of single coin.
Romi-
Papa, so you were listening our conversation?
17
Papa-
Nothing much Romi, Divya is right. In 1820 Danish physicist Hans Oersted proved
for the first time that moving charge or current in wire produced a magnetic field
in the surrounding area.
Romi-
But papa there is no wire in the pin box of Divya Di, yet there is a magnet in the
mouth of pen box.
Papa-
Yes Romi there are substance which are natural magnets. Naturally occurring
Magnetite ore is such a substance.
Divya-
Besides, there are permanent magnets.
Romi-
So the Magnet in the pin-box is a permanent magnet.
Divya-
Yes, all the electromagnets are temporary magnets.
Romi-
Papa but Divya di, could not answer why a substance become magnet. It is due
to electrons, Ok……. but How?
Papa-
Romi, I told you that when a charge moves, it creates a magnetic field.
Romi-
Understood but…………….
Papa-
Romi, Do you know how electrons move in an atom?
Romi-
Yes, every electrons move in two axes. One it moves like a top on its own axis.
Papa-
Yes…………
Romi-
…..And simultaneously it rotates around the nucleus, on elliptical path, called
orbit.
Papa-
Because electron is a moving negative charge, it creates magnetic field in two
axes.
Romi-
But papa every substance is made up of atoms and every atom contains
electrons too but every substance in not a magnet why?
Papa-
Romi in some substance atoms are so arranged that magnetic field of one
electron cancels the magnetic field of other electrons in the vicinity so there is
no bet magnetic field
Divya-
These substances are called “Non Magnetic Substances” such as Aluminum,
Wood, plastic etcetera.
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Papa-
But there are substance in which the magnetic field of these moving electrons
so arranged that they create a net magnetic field.
Divya-
These substances are called “Magnetic substance” such as Nickel cobalt and Iron.
Romi-
Papa but every piece of iron and every rod of Iron is not a magnet. How these
magnets are made?
Papa-
You know every electron in an atom produces a magnetic field, hence acts as a
tiny bar magnet.
Divya-
When this substance is kept with a powerful magnet of placed in a coil of wire all
these tiny magnets arrange themselves in such of way that their north poles are
on one side and south poles are on another side.
Romi-
North and south poles…..what are these?
Papa-
If we suspend a bar magnet freely by a thread, it rests with its ends pointing in
north and south. The end which is towards north is called “North Pole” and the
end rests towards south is called “South Pole”.
Romi-
Papa why a bar magnet behaves that way?
Divya-
Because earth itself behave like a huge magnet, its north pole to ward south pole
of the earth and its south pole towards earth’s north pole.
Romi-
Bur why our earth behaves that way papa?
Papa-
Romi because core of our earth is filled with molten iron. This earth magnet
protects earth from space radiation and solar winds.
(Change over music)
Atom-
So here I am…… the atom. Today I was with you in your journey from movement
of electrons to electricity…to magnetism. Hope we will go along a long way so
keep listening. We shall meet again on same day same time in this radio serial
(nonce of the serial). Till then good bye……..
(Signature tune..………………………………….........................................................................Fades out)
(Title song………………………………………………………………………………………………………………….Fades out)
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