Download holiday homework (physics)-2017

1
K.V. HALDWANI (SHIFT-1)
HOLIDAY HOMEWORK (PHYSICS)-2017
ASSIGNMENT-ELECTROSTATICS
UNIT 01
BELOW AVERAGE
1 Mark Questions
1.
2.
3.
4.
5.
6.
7.
Define capacitance of a capacitor. Give its unit.
Sketch the electric lines of force due to point charge(a)q>0
(b)q<0
Draw the electric lines of force due to electric dipole.
Draw the lines of force to represent a uniform electric field.
Why two electric lines of force do not intersect?
What physical quantity has S.I unit as
(1) N/m
(2) C-m
(3)V-m
What is amount of work done in moving a 100 nc change between two points 5 cm apart
on an equipotential surface?
8. Draw two equipotential surfaces due to a point charge.
9. What is the value of electric field inside a conductor?
10. Give two examples of conservative force in nature.
2 Marks Questions
1. Consider the situation shown in the figure given below. What will be the sign of q1 and
q2 ? Justify your answer also.
2. What orientation of an electric dipole in a uniform electric field corresponds to its stable
equilibrium? Give the reason also.
3. Derive the expression for the electric potential at a distance ‘r’ from a point change.
4. Derive an expression for the total work done in rotating an electric dipole through an
angle θ in a uniform electric field.
5. Derive an expression for the energy stored in a charged parallel plate capacitor with a
dielectric medium between its plates.
6. Calculate the distance between two protons such that the electrical repulsive force
between them is equal to the weight of either.
7. Calculate the potential at the centre of a square of a side 2 metre. Which Carries at its
four corners charges of +2nc, +1nc,-2nc and -3nc respectively.
8. When two capacitors of Capacitance C1 and C2 are connected in series the net
capacitance is 3μf.When connected in parallel its value is 16μF. Calculate the value of C1
&C2.
9. Force of attraction between two point charges placed at a distance‘d’ apart in a medium is
‘F’. What should be the distance in the same medium so that the force of attraction
between them becomes 9 F.?
10.Two point charge of +3x10-19 C are separated by a distance of 2.5m. Find the point on the
line joining them at which the electric field intensity is zero.
2
3 Marks Questions
1. Show that electric field ‘E’ itself is a source of energy with energy
density ½ Є0 E2 Jm-3.
2. An infinitely long condenser has linear charge density ‘λ’. Find the expression for electric
field intensity at a distance ‘R’ from it by using Gauss’s theorem of electrostatics.
3. State the theorem which relates the enclosed charge inside a closed surface with electric
flux through it. Use this theorem to obtain the electric field due to a uniform charged thin
spherical shell of surface charge density σ at a point (1)inside (2)at the surface
(3)outside, the shell.
4. Two equal and opposite charges are placed at a small distance apart. Fine the electric
field intensity due to system of charge at point lies on. (1)Axis of the system of charge (2)
Equatorial point to the axis of the system. Give the direction of electric field in both the
above cases with respect to dipole moment of the system of charges.
5. Two capacitors of equal capacitance when commented in series have net capacitance C1
and C2 when connected in parallel find the ratio C1/C2 ?
6. Define electric potential. Deduce an expression for electric potential at point at a distance
‘r’ from a point charge (q>0).
7. Assume C1, C2, C3 are three capacitors. Find the expression of equivalent capacitance if
they are connected in series and in parallel separately.
5 Marks Questions
1. Explain the basic Principle, Construction and Working of Van-de Graff generator with
the help of a Labelled diagram.
2. Derive an expression for the capacitance of a Parallel plate Capacitors with a Dielectric
medium of dielectric Constants ‘k’ between its plates. Also obtain the expression for the
energy stored in the above case.
3. State Gauss’s theorem in electrostatics .Using it derive the expression for the electric
field at any point due to an infinite plane sheet of charge of uniform Charge density ‘σ’
4. An electric dipole is held in a uniform electric field; calculate the work done in rotating it
through 1800.
5. Draw electric field lines between the plates of a parallel plate Capacitor with (1) Air and
(2) Dielectric as the medium. A parallel plate Capacitor with air as dielectric is
Connected to a power supply and charged to a potential difference Vo. After
disconnecting from power supply, a sheet of insulating material is inserted between the
plates completely filling the space between them.
How will its (1) Capacity (2) Electric field and (3) Energy Change?
Given that the
Capacity of Capacitor with air as medium is Co and Permittivity for air and medium are
Є0 & Є respectively.
AVERAGE
1 Mark Questions
1. Define 1 coulomb.
2. Write two properties of charge.
3. What do you mean by conservation of charge?
4. Is the force acting between two point charges q1 & q2 kef at some distance apart in air,
attractive or repulsive?
5. Define the terms, dielectric constant of a medium in terms of capacitance of a capacitor?
3
6. Define the term electric dipole moment. Is it scalar or vector quantity?
7. Define the term electric flux .Write its S.I.unit.
8. An electric dipole of dipole moment 20x10-6 C m and is enclosed by closed surface. What
is the net flux coming out of the surface?
9. Why does electric field inside a dielectric decrease when it is placed in an external
electric field?
10.An electrostatic field cannot be discontinuous. Why?
2 Marks questions
1. How does the Coulomb force between two Point charges depend upon the dielectric
constant of the intervening medium?
2. The distance of the field Point on the equatorial plane of a small electric digital is halved.
By what factor will the electric field, due to the dipole, change?
3. Write the condition under which the potential difference between the terminals of a
battery and its emf is equal.
4. Two plane sheets of charge densities + σ and - σ are kept in air as shown in figure. What
are the electric field intensities at point A & B?
A.
+σ
B.
-σ
5. Two charges q1 & q2, separated by small distance, satisfy the equation
q1+q2=0, What does it tell us about the charges?
3 Marks Questions
1 Two point charges +4e and +e units are separated by a distance ‘a’.
where should the third point charge be placed for it to be in
equilibrium?
2. Find the electric field intensity at a point on the axis of a uniformly charged ring.
3. An electric dipole of Strength 2cm is placed with its axis making an angle of 300 to a
uniform electric field of 105 N/C. if it experiences a torque of 10 3 Nm. calculate (i)
magnitude of charge on dipole and (ii) Potential energy of dipole
5 Marks Questions
1. Explain the basic Principle, Construction and Working of Van-de Graff generator with
the help of a Labelled diagram.
2. Derive an expression for the capacitance of a Parallel plate Capacitors with a Dielectric
medium of dielectric Constants ‘k’ between its plates. Also obtain the expression for the
energy stored in the above case.
3. State Gauss’s theorem in electrostatics .Using it derive the expression for the electric
field at any point due to an infinite plane sheet of charge of uniform Charge density ‘σ’
4. An electric dipole is held in a uniform electric field; calculate the work done in rotating it
through 1800.
5. Draw electric field lines between the plates of a parallel plate Capacitor with (1) Air and
(2) Dielectric as the medium. A parallel plate Capacitor with air as dielectric is
Connected to a power supply and charged to a potential difference Vo. After
disconnecting from power supply, a sheet of insulating material is inserted between the
plates completely filling the space between them .How will its (1) Capacity (2) Electric
field and (3) Energy Change? Given that the Capacity of Capacitor with air as medium
is Co and Permittivity for air and medium are Є0 & Є respectively.
4
ABOVE AVERAGE
1 Mark Questions
1. What is amount of work done in moving a 100 nc charge between two
Point 5 cm apart on an equipotential surface?
2. Draw two equipotential surface due to a point change.
3. What is the value of electric field inside a conductor?
4. Give two examples of conservative force in nature.
4. Define the term electric dipole moment. Is it a scalar or vector
Quantity?
5. Define the term electric flux write its S.I.unit.
6 An electric dipole of dipole moment 20x10-6 C m is enclosed by closed
Surface what is the net flux coming out of the surface?
7. Why does electric field inside a dielectric decrease when it is placed in
An external electric field?
8. An electrostatic field lines can not be discontinuous, why?
2 Marks Questions
1. How does the Coulomb force between two Point charges depend upon the dielectric
constant of the intervening medium?
2. The distance of the field Point on the equatorial plane of a small electric digital is halved
by what factor will the electric field, due to the dipole, change?
3. Write the condition under which the potential difference between the terminals of a
battery and its emf is equal.
4. Two plane sheets of charge densities + σ and - σ are kept in air as shown in figure. What
are the electric field intensities at point A & B?
A
+σ
B
- σ
5. Two charges q1 & q2, separated by small distance, satisfy the equation
q1+q2 = 0,
What does it tell us about the charges?
3 Marks questions
1. Four capacitors are connected as shown in figure given below.
the equivalent capacitance between the point X and Y.
Calculate
2. Calculate the capacitance of a capacitor shown in figure where K1.K2 and K3 are the Values
of dielectric constants
5
3. The capacitance of a parallel plate capacitor with plate area A and separation d in c. the
space between the plates is filled with two wedges of dielectric constants K1 and K2
respectively
C1
4.
C2
X
Y
C3
C5
Calculate effective capacitance between the Cterminals
A and B.
4
are given as
C1=10μF,C2=20 μF,C3=3 μF,C4=6 μF
5
Value of the capacitance
In the figure shown calculate the total flux of electrostatic field through
the spheres S1 and S2 the wire ‘AB’ Shown have has a Linear charge
density ‘λ’ given by λ=Kx where x is the distance measured along the
wire from the end A.
A
 = Kx
B
Q1
6
7
8
Two point charges +4e and +e units are separated by a distance ‘a’.
Where should the third point charge be placed for it to be in
Equilibrium?
Find the electric field intensity at any point on the axis of a uniformly
Charged ring.
An electric dipole of strength 2cm is placed with its axis making an
Angle of 300 to a uniform electric field of 105 N/C. if it experiences a
Torque of 10 3 Nm. calculate (i) magnitude of charge on dipole and
(ii) Potential energy of dipole
5 Marks questions
1. Derive an expression for the capacitance of a Parallel plate Capacitors with a Dielectric
medium of dielectric Constants ‘k’ between its plates. Also obtain the expression for the
energy stored in the above case.
2. State Gauss’s theorem in electrostatics .Using it derive the expression for the electric field at
any point due to an infinite plane sheet of charge of uniform Charge density ‘σ’
6
3. An electric dipole is held in a uniform electric field; calculate the work done in rotating it
through 1800.
4. Draw electric field lines between the plates of a parallel plate Capacitor with (1) Air and (2)
Dielectric as the medium. A parallel plate Capacitor with air as dielectric is Connected to a
power supply and charged to a potential difference Vo. After disconnecting from power
supply, a sheet of insulating material is inserted between the plates completely filling the
space between them.
How will its (1) Capacity (2) Electric field and (3) Energy Change?
Given that the
Capacity of Capacitor with air as medium is Co and Permittivity for air and medium are Є0
& Є respectively.
ASSIGNMENT-CURRENT ELECTRICITY
UNIT -0 2
BELOW AVERAGE
1 Mark Questions
1.
2.
3.
4.
5.
6.
7.
8.
Manganin is used for making standard resistors. Why?
A wire of resistivity  is stretched to double its length. What will be its new resistivity?
Of metals and alloys, which has greater value of temperature coefficient of resistance?
A carbon resistor is marked in coloured bands of red, black, orange and silver. What is
the resistance and tolerance value of the resistor?
A carbon resistor of 74k  is to be marked with rings of different colours for its
identification. Write the sequence of colours.
Name two material whose resistivity decreases with the rise of temperature.
Define potential gradient. Give its SI unit.
The colour code of carbon resistance is shown in fig. What is the value of the resistance?
Silver
Red
Violet Yellow
9. Why the potentiometer wire should be of uniform cross- sectional area?
10.State Ohm’s law.
11.Define Electrical conductivity of a conductor
12.A uniform wire resistance 10 ohm is cut into equal parts. These parts now connected in
parallel what will be the resistance of the combination.
13.On what principle meter bridge works.
2 Marks Questions
1. What are ohmic and non –ohmic conductors. Give one example of each .
2. Of the bulbs in a house, one glows brighter than the other. Which of the two has a large
resistance?
7
3.
4.
5.
6.
How can we increase the sensitivity of a potentiometer?
State kirchhoff’s loop rule.
A wire of resistance 2Ω is stretched double to its length.What is its new resistance?
A carbon resistor is marked in coloured bands of yellow, green, blue and silver. What is
the resistance and tolerance value of the resistor?
7. A 5Ω resistance is connected in series with a cell of internal resistance 0.2Ω and emf
10V.What is the current flowing in the circuit?
8. What is internal resistance of a cell. Derive an expression for it.
9. In the arrangement of resistor given below find the value of current through 3Ω resistor.
10.V-I graph for a metallic wire at two different temperatures T1 and T2 is shown in the
following figure which of the two temperature is higher and why?
3 Marks Questions
1. With the help of a circuit diagram, briefly explain how a meter bridge can be used to
find the unknown resistance of a given wire. State the formula used.
2. Define resistivity of a conductor. Explain the variation of resistance with temperature in
a) metallic conductor b) semi conductor.
3. what are the factors upon which the resistance of a conductor depends. Give the
corresponding relation and the SI unit of resistivity.
4. Derive the relation between drift velocity of electron and electric current.
5. Two wires of equal lengths, one of copper and the other of manganin have the same
resistance. Which wire is thicker?
6. How would you compare the emf’s of two cells by using a potentiometer.
7. Resistance of a carbon resistor is 450  ± 5% .Show the resistor with appropriate
colour bands.
8. A parallel combination of three resistors takes a current of 5A from a 10V supply . If
the value of resistance of each resistor be the same, find its value.
9. Find the resistance of the network shown in the figure between points A and B
10 State Ohm’s Law. Give its mathematical relation. Show the graph
between V & I for ohmic conductors.
8
5 Marks Questions
1.
( i) Give the principle of potentiometer.
ii) A potentiometer wire of length 10m has a resistance of 10 .It is connected to a
cell of emf 2V and internal resistance 1 .Calculate the length of the balance point for a
cell of emf 1.5V.
2. Explain the principal of wheatstone bridge for determining an unknown resistance.
Name the apparatus which works on this principle. How unknown resistance is calculated
by that device?
AVERAGE
1 Mark Questions
1. A copper wire of resistivity  is stretched to reduce its diameter to half of its previous
value .What will be its new resistivity?
2. Why potentiometer is preferred over voltmeter to measuring e.m.f.?
3. If a wire of resistivity’’ is stretched to thrice its initial length, what will be its new
resistivity?
4. which has greater resistance (i) milliammeter or ammeter and (ii) millivoltmeter or
voltmeter?
5. Who do we prefer a potentiometer to measure e.m.f. of a cell rather than a voltmeter?
6. A wire has colours coding of red, blue, gold and silver .Give its resistance.
7. Why is potentiometer named as potentiometer?
8. Why do we prefer a potentiometer with a longer bridge wire?
9. Out of two bulbs marked 25 W and 100 W which one has higher resistance?
10.Write Kirchhoff’s junction rule.
2 Marks Questions
1. Out of an ammeter and a voltmeter, which of the two has higher resistance and why?
2. Why does the resistivity of semi – conductors and insulator decrease with increase of
temperature?
3. The letter A consists of a uniform wire of resistance 1 ohm cm-1.The sides of the letter are
40 cm long and the crosspiece 10 cm long divides the sides in the ratio 1:3 from the apex.
Find the resistance of the letter between the two end of the legs.
4. The resistance of a tungsten filament at 150 oC is 133 ohm. What will be the resistance at
500oC? The temperature coefficient of resistance of tungsten at 0oC is 0.0045 oC-1.
5. Storage battery of a car has an e.m.f.of 12 V. If the internal resistance of the battery is 0.4
 , what is the maximum current that can be drawn from the battery?
6. Using meter bridge it is advised to obtain null point in the middle of the wire. Why?
7. Explain with the help of graph the variation of conductivity with temperature for a
metallic conductor.
8. Distinguish between electromotive force and terminal potential difference of a cell.
9. Why connecting wires are made up of copper?
10.Derive the relation between drift velocity of electron and electric current.
11.Discuss the effect of temperature on the resistivity of metals.
3 Marks Questions
9
1. Define resistivity.Give its S.I. unit. Show the resistance R of a conductor is given by
ml
Where symbols have their usual meanings.
ne 2 A
2. State and discuss Kirchhoff’s current and voltage law.
3. Give the principle of a potentiometer. How would you compare the emf of two cells
using this.
4. How would you calculate the value of unknown resistance by using a meter bridge.
5. The potential difference across a potentiometer wire 10m long is 3volt.Calculate the emf
of the cell which is balanced by 120cm long wire.
6. Calculate the electrical conductivity of the material of a conductor of length 3m and area
of cross section 0.5mm2 having a resistance of 5.
7. In the network given below, use kirchhoff’s laws to calculate the values of electric
currents I1, I2 & I3.
8. Two cells E1 and E2 in the given circuit diagram have an emf of 5V and
9V and
internal resistance of 0.3Ω and 1.2Ω respectively. Calculate the value of current flowing
through 3Ω resistor.
9.
A voltmeter has a resistance of 20 kΩ. When it is connected in series with an external
resistance R across a 220V supply, it reads 160V. What is the value of R?
10. Derive a relation between current density and conductivity of the material. Give S.I.
Unit of conductivity too.
5 Marks Questions
1. In the network shown here, find the following:
(a)currents I1,I2,I3
(b)Terminal potential difference of each battery.
Consider 6 to be the internal resistance of 6V battery and 4 to be internal resistance of
8V battery.
6V
A
I1
F
8V
A
B
A
C
I2
A
E
D
I3
2. The four arms of a wheat stone bridge have the following resistances AB=100Ω BC=10
Ω, CD=5 Ω and DA=60 Ω. The galvanometer of 15 Ω resistance is connected across BD.
10
Calculate the current through the galvanometer when at potential difference of 10V is
maintained across AC.
B
100Ω
10Ω
A
C
60Ω
D
50Ω
10V
3. Twelve similar wires each of resistance r are connected to form a cube .Calculate the
equivalent resistance between the ends of a side.
ABOVE AVERAGE
1 Mark Questions
1. Why a voltmeter is always connected in parallel with a circuit element across which
voltage is to be measured?
2. Two wires, one of manganin and the other of copper have equal lengths and equal
resistances. Which one of this wire will be thicker?
3. Why is the ten –wire potentiometer more sensitive than a four –wire one?
4. What is the internal resistance of cell? On what factors it depends ?
5. A metallic wire of resistance 20 is stretched to twice its length. What will be its new
resistance?
6. A copper wire of resistivity p (rho) is stretched to make it 5% longer. Find the % change
in its resistance.
7. Of which material is a potentiometer wire normally made and why?
8. Define mobility of electrons and give its SI units.
9. Define relaxation time of electrons in a conductor.
10. Discuss the effect of temperature on the resistivity of metals.
2 Marks Questions
1. Aset of n identical resistors , each of resistor R ohm , when connected in series have an
effective resistance X ohm , and when the resistors are connected in parallel ,their
effective resistance isY ohm . Find the relation between R , Xand Y.
2. Explain the principle on which the working of a potentiometer is based. Why is the use of
a potentiometer preferred over that of a voltmeter for measurement of e.m.f. of a cell?
3. At room temperature (27.0oC), the resistance of a heating element is 100 ohm. What is
the temperature of the element, if the resistance is found to be 117 ohm? Given that the
temperature coefficient of the material of the resistor is 1.70 x 10-4 oC-1.
11
-1
4. You are giving a 8 resistor. What length of constantan wire of resistance 12m
should be joined in parallel with it to get a value of 6 ohms?
5. Resistances of 1,2 and 3 are given .How will you combine them to get an equivalent
resistance of 6 and 11/3 ?
6. Draw a graph to show the variation of a resistance of a metal wire with its diameter
keeping the length and temperature constant?
7. Three identical cells each of emf 2V and unknown internal resistance are connected in
parallel this combination is connected to a 5  resistor. if the terminal voltage across the
cell is 3V .what is the internal resistance of each cell.
8. Find the circuit current from the given arrangement and also find voltage across 5Ω
resistor.
9. Five resistors are connected as shown in the figure. Find the equivalent resistance
between the points A & C.
10.Differentiate between resistance and resistivity. Write their S.I. units too.
3 Marks Questions
1. The length of a potentiometer wire is 600cm and it carries a current of 40 mA.For a cell
of emf 2V and internal resistance 10,the null point is found to be at 500cm.If a
voltmeter is connected across the cell, the balancing length is decreased by 10cm.Find 1)
the resistance of whole wire. ii) Reading of voltmeter, and iii) resistance of voltmeter.
2. Three identical cells each of emf 4V and internal resistance ‘r’are connected in series to
a 6 resistor .If the current flowing in the circuit is 1.5A,Calculate i) the internal
resistance of each cell and ii) the terminal voltage across the cells.
3. Derive ohm’s law using the concept of drift velocity
4. Two wires of the same material having lengths in the ratio 1:2 and diameters in the ratio
2:3 are connected in series with an accumulator of emf E . Compute the ratio of the
potential difference across the two wires.
5. Give the principle of a potentiometer. How would you compare the emf of two cells
using this.
6. The potential difference across a potentiometer wire 12m long is 6volt.Calculate the emf
of the cell which is balanced by 150cm long wire.
7. State the principle of potentiometer and describe a method to find the internal resistance
of a primary cell.
8. In the given network, find the values of the currents I1, I2 & I3.
12
9. A potentiometer wire of length 100 cm has a resistance of 10Ω. It is connected with
series with a resistance 5Ω and an accumulator of emf 3V. A source of 1.2V is balanced
against a length ‘L’ of the potentiometer wire. Find the value of ‘L’.
10.Calculate the equivalent resistance between A and B of the electrical network given
below. If a battery of emf 8V and internal resistance 1Ω is connected across the points A
and B, calculate the current drawn by the circuit.
5 Marks Questions
1. Network PQRS is made as under. SR has a battery of 4V and negligible resistance with
positive terminal connected to S, QR has a resistance of 60 Ω. PS has a battery of 5V and
negligible resistance with positive terminal connected to S, PQ has a resistance of 200 Ω.
If a milliammeter of 20 Ω resistance is connected between Q and S , Calculate the
reading of the milliammeter.
P
Q
5V
V
S
R
4V
2. Deduce the condition for balance in a wheatstone bridge. Using the principle of
wheatstone bridge, describe the method to determine the specific resistance of a wire in
the laboratory. Draw the circuit diagram and write the formula used.
3. State kirchhoff’s laws of electrical network. Using kirchhoff’s laws, calculate the
potential difference across the 8ohm resistor.
13
COMMUNICATION SYSTEM
UNIT – 10
BELOW AVERAGE
1 Mark Questions
1.
2.
3.
4.
5.
6.
?
7.
8.
9.
What is amplitude modulation ?
What is detection ?
What is bandwidth of signal ?
Name the essential parts of communication system ?
Give One example where the process of modulation is done ?
What type of modulation is useful for sound signal in television broadcasting
What does side band in an AM wave represent ?
Give one advantage of digital communication over analog communication ?
What are analog and digital signals ?
2 Marks Questions
1.
2.
3.
4.
5.
Draw a block diagram of Diode detector ?
Draw a block diagram of Communication system ?
What is the need of amplitude modulation ?
How does Ionosphere help in transmission of radio waves over long distances ?
what mode of communication is employed for the transmission of TV signals ?
Explain why TV transmission towers are usually made very high ?
6. Why ground wave propagation is not suitable for the higher frequencies ?
7. A transmitting antenna at the top of a tower has a height 32m and the height of
the receiving antenna is 50m. What is the maximum distance between them for
satisfactory communication in LOS mode ?
3 Marks Questions
1. What is amplitude modulation ? Show that the bandwidth of amplitude
modulated signal is twice the bandwidth of modulating signal ?
2. What is meant by modulation ? Explain with the help of a block diagram how
the process of modulation is carried out in radio broadcast ?
3. Describe propagation through ground wave, Sky wave and space wave.
Describing their limits and limitations ?
4. What do you mean by sampling of an analog signal ? Describe advantage of
digital communication system over analog communication system ?
5. A transmitting antenna at a top of a tower has a height 42m and the height of
receiving antenna is 50m. What is the maximum distance between them for
satisfactory communication in LOS mode ?
14
What is the importance of modulation index ? Write the limitation of
amplitude modulation ?
AVERAGE
1 Mark Questions
1. If broadcasting station is transmitted but not modulated, what is heard in the
receiver ?
2. A message signal of frequency 10 KHz to modulate a carrier frequency of I
MHz. What is the sideband prouduced ?
3. A intelligence signal with a bandwidth of 100 KHz is to be communicated over
a distance of 10Km. Suggest an appropriate form of communication channel ?
4. On what factors does the ground wave propagation depend ?
5. What change is carried out is amplitude modulation ?
2 Marks Questions
1.
2.
3.
4.
5.
6.
7.
8.
9.
What is carrier communication ?
Why is carrier communication essential for radio engineering ?
What is the importance of modulation factor in amplitude modulation ?
Why does amplitude modulation give noisy reception ?
Why do AM receiver lack audio quality ?
Why is AM so insufficient ?
What are the desirable characteristics of a Diode detector ?
What are uplink and downlink in satellite communication ?
What is communication satellite ?
3 Marks Questions
1. What is an optical detector ? State its three essential characteristics. Name the
Factors which decides how good a detector is ?
2. A ground receiver station is receiving at a signal at 5 MHz and 100 MHz
transmitted from a ground transmitter at a height of 300 m located at a distance
of 100 Km. Identify whether it is coming via space wave or sky wave
communication or satellite transponder. Justify ?
3. Is it necessary for a transmitting antenna to be at the same height of the
receiving antenna for line of sight communication.? A TV transmitting antenna
is 81 m tall . How much service area can it cover if the receiving antenna is at
the ground level ?
4. A modulating signal is a square wave as shown in the Fig-
The carrier wave is given by C (t) = 2 Sin ( 8 π t) volts.
(i)
Sketch the amplitude modulated waveform ?
(ii) What is the modulation Index ?
15
5. The maximum peak to peak voltage at an AM wave is 16 milli volts and minimum
voltage is 4 milli volt. Calculate the modulation factor or modulation index ?
6. What is amplitude modulation ? Find the expression for amplitude modulated
wave. Write its advantage and disadvantage ?