All Exams >
JEE >
Physics for JEE Main & Advanced >
All Questions
All questions of Electromagnetic Induction for JEE Exam
in Weber in closed circuit of resistance 15 ohm varies with time t sec as
A circular coil of area 200 cm2 and 25 turns rotates about its vertical diameter with an angular speed of 20 ms-1 in a uniform horizontal magnetic field of magnitude 0.05 T. The maximum voltage induced in the coil is- a)0.5 V
- b)1.5 V
- c)2.5 V
- d)2.0 V
Correct answer is option 'A'. Can you explain this answer?
A circular coil of area 200 cm2 and 25 turns rotates about its vertical diameter with an angular speed of 20 ms-1 in a uniform horizontal magnetic field of magnitude 0.05 T. The maximum voltage induced in the coil is
a)
0.5 V
b)
1.5 V
c)
2.5 V
d)
2.0 V
|
Hansa Sharma answered |
It is induced EMF of periodic EMI, So formula is:
E= NBAw
Here w is angular speed.
E= NBAw
Here w is angular speed.
So, E = 25×0.05×200×20/10000 =0.5V
Eddy currents have negative effects. Because they produce- a)Harmful radiation
- b)Heating and damping
- c)Damping only
- d)Heating only
Correct answer is option 'B'. Can you explain this answer?
Eddy currents have negative effects. Because they produce
a)
Harmful radiation
b)
Heating and damping
c)
Damping only
d)
Heating only
|
Mamali . answered |
When a conductive material is subjected to a time-varying magnetic flux, eddy currents are generated in the conductor. These eddy currents circulate inside the con- ductor generating a magnetic field of opposite polarity as the applied magnetic field. The interaction of the two magnetic fields causes a force that resists the change in magnetic flux. However, due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat and the force will die out. As the eddy currents are dissipated, energy is removed from the system, thus producing a damp- ing effect.
In the dead beat galvanometer, the coil is wound on a frame made of:- a)good conductor
- b)non magnetic material
- c)bad conductor
- d)magnetic material
Correct answer is option 'A'. Can you explain this answer?
In the dead beat galvanometer, the coil is wound on a frame made of:
a)
good conductor
b)
non magnetic material
c)
bad conductor
d)
magnetic material
|
Nikita Singh answered |
Aluminum is used as a coil which is a good conductor.
Dead beat galvanometer:
Dead beat galvanometer:
Suppose there are two coils of length 1m with 100 and 200 turns and area of cross section of 5 x 10-3 m2. Find the mutual inductance.- a)
- b)
- c)
- d)
Correct answer is option 'C'. Can you explain this answer?
Suppose there are two coils of length 1m with 100 and 200 turns and area of cross section of 5 x 10-3 m2. Find the mutual inductance.
a)
b)
c)
d)
|
Om Desai answered |
The magnetic field through the secondary of N2 turns of each other of area S is given as,
N2= Φ2=N2(BS)
=μ0n1N2i1S
M= N2Φ2/i1
M= μ0n1N2S
Substituting the values.
M=(4πx10-7) x100x200x5x10-3
=1287142.86x10-10
=12.57x10-5H
N2= Φ2=N2(BS)
=μ0n1N2i1S
M= N2Φ2/i1
M= μ0n1N2S
Substituting the values.
M=(4πx10-7) x100x200x5x10-3
=1287142.86x10-10
=12.57x10-5H
The unit of self inductance of a coil is- a)volt s A-1
- b)volt-1s-1 A-1
- c)volt s-1 A-1
- d)volt s-1 A
Correct answer is option 'A'. Can you explain this answer?
The unit of self inductance of a coil is
a)
volt s A-1
b)
volt-1s-1 A-1
c)
volt s-1 A-1
d)
volt s-1 A
|
Infinity Academy answered |
Now, e=L(di/dt)
L=e/(di/dt)
1 henry=1 volt/(1 ampere/second)
L=e/(di/dt)
1 henry=1 volt/(1 ampere/second)
If the current in primary coil changes from 5 A to 2 A in 0.03 sec and the induced e.m.f. is 1000 volts, find the mutual induction- a)0.1 H
- b)0.01 H
- c)10 H
- d)1 H
Correct answer is option 'C'. Can you explain this answer?
If the current in primary coil changes from 5 A to 2 A in 0.03 sec and the induced e.m.f. is 1000 volts, find the mutual induction
a)
0.1 H
b)
0.01 H
c)
10 H
d)
1 H
|
Lavanya Menon answered |
As φ =mi
now take change in flux
dφ/dt=d(mi)/dt
we can write it as
dφ/ dt= m Δi/Δt
-e=m(2-5)/0.03
e=3m/0.03
1000=300m/3
m=10
now take change in flux
dφ/dt=d(mi)/dt
we can write it as
dφ/ dt= m Δi/Δt
-e=m(2-5)/0.03
e=3m/0.03
1000=300m/3
m=10
Which of the following will not increase the size and effect of eddy current?- a)Low resistivity materials
- b)Strong magnetic field
- c)Thicker material
- d)Thinner material
Correct answer is option 'D'. Can you explain this answer?
Which of the following will not increase the size and effect of eddy current?
a)
Low resistivity materials
b)
Strong magnetic field
c)
Thicker material
d)
Thinner material
|
|
Hansa Sharma answered |
Stronger magnetic field, thicker material and low resistivity material will increase the size and effect of eddy current whereas thinner material will reduce the effect of eddy currents.
Which of the following quantities can be written in SI units in K gm2 A-2 S-3 ?- a)Resistance
- b)Inductance
- c)Capacitance
- d)Magnetic flux
Correct answer is option 'A'. Can you explain this answer?
Which of the following quantities can be written in SI units in K gm2 A-2 S-3 ?
a)
Resistance
b)
Inductance
c)
Capacitance
d)
Magnetic flux
|
|
Nikita Singh answered |
The dimensional formula of a given unit is [ML2T−3A−2].
So, from the given option only resistance has this dimensional formula so resistance is the correct answer.
So, from the given option only resistance has this dimensional formula so resistance is the correct answer.
The mutual induction does not depend on which of the following factors- a)Number of turns
- b)Shape of the two coils
- c)Distance between two coils
- d)Current through both the coils
Correct answer is option 'D'. Can you explain this answer?
The mutual induction does not depend on which of the following factors
a)
Number of turns
b)
Shape of the two coils
c)
Distance between two coils
d)
Current through both the coils
|
Rajat Patel answered |
The factors which determine the value of mutual inductance are —
a. number of turns of the coils
b. separation of coils
c. geometric shape and size of coils
d. angular orientation between the coils
Identify the type of commercial motor which works as a consequence of eddy currents.- a)Compressors
- b)Induction motors
- c)Turbines
- d)Hydropowered motors
Correct answer is option 'B'. Can you explain this answer?
Identify the type of commercial motor which works as a consequence of eddy currents.
a)
Compressors
b)
Induction motors
c)
Turbines
d)
Hydropowered motors
|
Varun Kapoor answered |
A rotating magnetic field is produced employing two single-phase currents. A metallic rotor placed inside the rotating magnetic field starts rotating due to large eddy currents produced in it. These motors are commonly used in fans.
Eddy currents do not cause:- a)sparking
- b)heating
- c)loss of energy
- d)damping
Correct answer is option 'A'. Can you explain this answer?
Eddy currents do not cause:
a)
sparking
b)
heating
c)
loss of energy
d)
damping
|
Arjun Singhania answered |
During braking, the metal wheels are exposed to a magnetic field from an electromagnet, generating eddy currents in the wheels. So, by Lenz's law, the magnetic field formed by the Eddy current will oppose its cause. Thus the wheel will face a force opposing the initial movement of the wheel.
Whenever the magnetic flux (
) linked with a coil changes the emf is induced in the circuit, This emf lasts- a)as long as the change in flux continues.
- b)for a long time
- c)for a short time
- d)forever
Correct answer is option 'A'. Can you explain this answer?
Whenever the magnetic flux () linked with a coil changes the emf is induced in the circuit, This emf lasts
) linked with a coil changes the emf is induced in the circuit, This emf lastsa)
as long as the change in flux continues.
b)
for a long time
c)
for a short time
d)
forever
|
Idamangala Merlin answered |
Answer a it is faraday 1st law
A magnet is moved towards the coil (a) quickly and (b) slowly, and then the work done is- a)does not depend on the motion of the magnet.
- b)smaller in case (a)
- c)equal in both cases
- d)larger in case (a)
Correct answer is option 'D'. Can you explain this answer?
A magnet is moved towards the coil (a) quickly and (b) slowly, and then the work done is
a)
does not depend on the motion of the magnet.
b)
smaller in case (a)
c)
equal in both cases
d)
larger in case (a)
|
Jayant Mishra answered |
A magnet is moved towards the coil (a) quickly and (b) slowly, and then the work done is This is because when the magnet is moved quickly, opposing emf induced in the coil will be more.
In which of the following cases with a bar magnet and the coil no induced emf is induced.- a)When there is no relative motion between the magnet and the coil.
- b)When the coil is moved towards or away from the magnet.
- c)When the magnet is taken away from the coil.
- d)When the magnet is inserted into the coil.
Correct answer is option 'A'. Can you explain this answer?
In which of the following cases with a bar magnet and the coil no induced emf is induced.
a)
When there is no relative motion between the magnet and the coil.
b)
When the coil is moved towards or away from the magnet.
c)
When the magnet is taken away from the coil.
d)
When the magnet is inserted into the coil.
|
|
Lavanya Menon answered |
This is because induced emf directly depends on relative motion between the magnet and coil, but if there is no relative motion between them, there will be no emf induced.
A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced currents in wires AB and CD are 
- a) B to A and D to C
- b)A to B and C to D
- c)A to B and D to C
- d)B to A and C to D
Correct answer is option 'A'. Can you explain this answer?
A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced currents in wires AB and CD are
a)
B to A and D to C
b)
A to B and C to D
c)
A to B and D to C
d)
B to A and C to D
|
Preeti Khanna answered |
Consider the surface facing upwards having points A, B, C and D in anticlockwise direction when viewing towards the surface from above. Let this be S
flux = S×B
As the flux increases, by Lenz's Law the induced current will be in the direction C B A D C, so as to oppose the increase in flux.
flux = S×B
As the flux increases, by Lenz's Law the induced current will be in the direction C B A D C, so as to oppose the increase in flux.
Two pure inductors are connected in series, if their self inductance is L. Find the total inductance- a)0.5L
- b)L
- c)2L
- d)0.2L
Correct answer is option 'C'. Can you explain this answer?
Two pure inductors are connected in series, if their self inductance is L. Find the total inductance
a)
0.5L
b)
L
c)
2L
d)
0.2L
|
Sidharth Gupta answered |
Its same as in resistor series formula
The role of inductance is equivalent to:- a)energy
- b)force
- c)inertia
- d)momentum
Correct answer is option 'C'. Can you explain this answer?
The role of inductance is equivalent to:
a)
energy
b)
force
c)
inertia
d)
momentum
|
|
Rahul Bansal answered |
Self induction is that phenomenon in which a change in electric current in a coil produces an induced emf in the coil itself.
Now, it is also known as inertia of electricity as for if we were to change electric current through a current carrying coil it will tend to oppose any further change in its emf. This is similar to inertial behavior in mechanics where bodies in either rest or motion tend to oppose any change in their state. Here mass is the inertial property analogous to self inductance.
A coil of area 10 cm² of 20 turns is placed in uniform magnetic field of 104 gauss. The normal to the plane of the coil makes an angle of 60° with the magnetic field. The flux in maxwell through the coil is
- a)105
- b)106
- c)103
- d)104
Correct answer is option 'B'. Can you explain this answer?
A coil of area 10 cm² of 20 turns is placed in uniform magnetic field of 104 gauss. The normal to the plane of the coil makes an angle of 60° with the magnetic field. The flux in maxwell through the coil is
a)
105
b)
106
c)
103
d)
104
|
|
Hansa Sharma answered |
The no-load current drawn by transformer is usually what per cent of the full-load current ?- a)0.2 to 0.5 per cent
- b)2 to 5 per cent
- c)12 to 15 per cent
- d)20 to 30 per cent
Correct answer is option 'B'. Can you explain this answer?
The no-load current drawn by transformer is usually what per cent of the full-load current ?
a)
0.2 to 0.5 per cent
b)
2 to 5 per cent
c)
12 to 15 per cent
d)
20 to 30 per cent
|
Baishali Chakraborty answered |
The no load current is about 2-5% of the full load current and it accounts for the losses in a transformer. These no-load losses include core(iron/fixed) losses, which contains eddy current losses & hysteresis losses and the copper(I2*R) losses due to the no Load current.
Eddy currents can be induced in- a)Metal Blocks
- b)Wires
- c)Both metal blocks and wires
- d)Insulators
Correct answer is option 'C'. Can you explain this answer?
Eddy currents can be induced in
a)
Metal Blocks
b)
Wires
c)
Both metal blocks and wires
d)
Insulators
|
Anusaya Swain answered |
Eddy currents are produced by varying magnetic field in solid plates, blocks and wires.
Find the dimension of the quantity 
, where symbols have usual meaning.- a)A-1
- b)A-2
- c)A
- d)A2
Correct answer is option 'A'. Can you explain this answer?
Find the dimension of the quantity , where symbols have usual meaning.
, where symbols have usual meaning.a)
A-1
b)
A-2
c)
A
d)
A2
|
|
Harsh Singhal answered |
On multiply w in upper & lower side we get inductive reactance & capacitive reactance
so on cancel out in term of unit we get R/V
which is equal to 1/i= A-1
so on cancel out in term of unit we get R/V
which is equal to 1/i= A-1
An air-cored solenoid with length 30 cm, area of cross-section 25 cm2 and number of turns 500, carries a current of 2.5 A. The current is suddenly switched off in a brief time of 10−3s. Average back emf induced across the ends of the open switch in the circuit is- a)6.5 V .
- b)4.6 V
- c)4.5 V
- d)5 V3.
Correct answer is option 'A'. Can you explain this answer?
An air-cored solenoid with length 30 cm, area of cross-section 25 cm2 and number of turns 500, carries a current of 2.5 A. The current is suddenly switched off in a brief time of 10−3s. Average back emf induced across the ends of the open switch in the circuit is
a)
6.5 V .
b)
4.6 V
c)
4.5 V
d)
5 V3.
|
Ishani Patel answered |
When a wire loop is rotated in a magnetic field, the direction of induced emf changes once in each- a)2 revolutions
- b)1 revolution
- c)1/2 revolution
- d)12 revolution
Correct answer is option 'C'. Can you explain this answer?
When a wire loop is rotated in a magnetic field, the direction of induced emf changes once in each
a)
2 revolutions
b)
1 revolution
c)
1/2 revolution
d)
12 revolution
|
|
Rajeev Saxena answered |
Flux of the magnetic field through the loop is ϕ=Bπr2coswt
Where θ= angle the normal makes with the portion of the loop in duced emf.
∈=wBπr2sinwt
These is zero when wt=nπ ie
When θ=0,π,2π.... etc.
So, the induced emf changes direction every half rotation.
Inductance is a _______ quantity. Its dimension is ________.- a)scalar, [ML2T-2 A-2]
- b)scalar, [MLT-2 A-2]
- c)vector, [ML2T-2 A-2]
- d)scalar, [ML2T2 A-2]
Correct answer is option 'A'. Can you explain this answer?
Inductance is a _______ quantity. Its dimension is ________.
a)
scalar, [ML2T-2 A-2]
b)
scalar, [MLT-2 A-2]
c)
vector, [ML2T-2 A-2]
d)
scalar, [ML2T2 A-2]
|
|
Preeti Iyer answered |
It is also called the Coefficient of induction. Coefficient of induction is about the ratio of current induced with respect to magnetic flux. This constant of proportionality is known as Inductance. It is a scalar quantity.
The dimension of inductance- M1·L2·T−2·A−2
The dimension of inductance- M1·L2·T−2·A−2
In electromagnetic induction, line integral of induced field E around a close path is __________, induced electric field is ___________.- a)Zero, Non Conservative
- b)Non zero, Conservative
- c)Zero, Conservative
- d)Non zero, Non Conservative
Correct answer is option 'D'. Can you explain this answer?
In electromagnetic induction, line integral of induced field E around a close path is __________, induced electric field is ___________.
a)
Zero, Non Conservative
b)
Non zero, Conservative
c)
Zero, Conservative
d)
Non zero, Non Conservative
|
|
Kalyan Chavan answered |
In electromagnetic induction, line integral of induced field E around a close path is non zero, and induced electric field is non conservative.
The horizontal component of the earth's magnetic field at a place is 3 × 10-4 T and the dip is tan-1(4/3). A metal rod of length 0.25 m placed in the north-south position is moved at a constant speed of 10 cm/s towards the east. Find the e.m.f induced in the rod. in mV
Correct answer is '1'. Can you explain this answer?
The horizontal component of the earth's magnetic field at a place is 3 × 10-4 T and the dip is tan-1(4/3). A metal rod of length 0.25 m placed in the north-south position is moved at a constant speed of 10 cm/s towards the east. Find the e.m.f induced in the rod. in mV
|
Manish Aggarwal answered |
AB and CD are smooth parallel rails, separated by a distance l, and inclined to the horizontal at an angle q. A uniform magnetic field of magnitude B, directed vertically upwards, exists in the region. EF is a conductor of mass m, carrying a current i. if B is normal to the plane of the rails
- a)Bil = mg tan q
- b)Bil = mg sin q
- c)Bil = mg cos q
- d)Equilibrium cannot be reached
Correct answer is option 'B'. Can you explain this answer?
AB and CD are smooth parallel rails, separated by a distance l, and inclined to the horizontal at an angle q. A uniform magnetic field of magnitude B, directed vertically upwards, exists in the region. EF is a conductor of mass m, carrying a current i. if B is normal to the plane of the rails
a)
Bil = mg tan q
b)
Bil = mg sin q
c)
Bil = mg cos q
d)
Equilibrium cannot be reached
|
|
Om Desai answered |
As seen from the image, in the direction of magnetic field
mgsinθ=il×B
mgsinθ=ilB
mgsinθ=il×B
mgsinθ=ilB
two different arrangements in which two square wire frames of same resistance are placed in a uniform constantly decreasing magnetic field B. 
The value of magnetic flux in each case is given by- a) Case I : f = p(L2 + ℓ2 ) B; Case II : f = p(L2 – ℓ2) B
- b)Case I : f = p(L2 + ℓ2) B; Case II : f = p(L2 + ℓ2) B
- c)Case I : f = (L2 + ℓ2) B; Case II : f = (L2 – ℓ2) B
- d)Case I : f = (L + ℓ)2 B; Case II : f = (L – ℓ)2 B
Correct answer is option 'C'. Can you explain this answer?
two different arrangements in which two square wire frames of same resistance are placed in a uniform constantly decreasing magnetic field B.
The value of magnetic flux in each case is given by
a)
Case I : f = p(L2 + ℓ2 ) B; Case II : f = p(L2 – ℓ2) B
b)
Case I : f = p(L2 + ℓ2) B; Case II : f = p(L2 + ℓ2) B
c)
Case I : f = (L2 + ℓ2) B; Case II : f = (L2 – ℓ2) B
d)
Case I : f = (L + ℓ)2 B; Case II : f = (L – ℓ)2 B
|
|
Himanshu Jhajharia answered |
A circular coil of radius 8.0 cm and 20 turns is rotated about its vertical diameter with an angular speed of 50 rad s-1 in a uniform horizontal magnetic field of magnitude 3×10-2 T. If the coil resistance is 10Ω, maximum emf induced in the coil,maximum value of current in the coil and average power loss due to Joule heating are- a)0.603 V, 0.0303 A,0.018 W
- b)0.603 V, 0.0603 A,0.038 W
- c)0.603 V, 0.0603 A,0.018 W .
- d)0.303 V, 0.0603 A,0.018 W
Correct answer is option 'C'. Can you explain this answer?
A circular coil of radius 8.0 cm and 20 turns is rotated about its vertical diameter with an angular speed of 50 rad s-1 in a uniform horizontal magnetic field of magnitude 3×10-2 T. If the coil resistance is 10Ω, maximum emf induced in the coil,maximum value of current in the coil and average power loss due to Joule heating are
a)
0.603 V, 0.0303 A,0.018 W
b)
0.603 V, 0.0603 A,0.038 W
c)
0.603 V, 0.0603 A,0.018 W .
d)
0.303 V, 0.0603 A,0.018 W
|
Bhavana Banerjee answered |
e = NBAω = 20 x 3 x 10-2 x (3.14 x 0.08 x 0.08) x 50 = 0.603C
average power loss due to joule heating
The principle of electromagnetic induction is used in which of the following phenomenon- a)Generation of electricity in hydroelectricity.
- b)Generation of electricity in nuclear power plant.
- c)Generation of electricity in thermal power plant.
- d)Generation of electricity from wind energy.
Correct answer is option 'A'. Can you explain this answer?
The principle of electromagnetic induction is used in which of the following phenomenon
a)
Generation of electricity in hydroelectricity.
b)
Generation of electricity in nuclear power plant.
c)
Generation of electricity in thermal power plant.
d)
Generation of electricity from wind energy.
|
|
Animesh Nhagal answered |
Electrical generators (such as hydroelectric dams) where mechanical power is used to move a magnetic field past coils of wire to generate voltage
Figure shows a bar magnet and a long straight wire W, carrying current into the plane of paper. Point P is the point of intersection of axis of magnet and the line of shortest distance between magnet and the wire. If p is the midpoint of the magnet, then which of the following statements is correct ? 
- a) Magnet experiences a torque in clockwise direction
- b)Magnet experiences a torque in anticlockwise direction
- c)Magnet experiences a force, normal to the line of shortest distance
- d)Magnet experiences a force along the line of shortest distance
Correct answer is option 'D'. Can you explain this answer?
Figure shows a bar magnet and a long straight wire W, carrying current into the plane of paper. Point P is the point of intersection of axis of magnet and the line of shortest distance between magnet and the wire. If p is the midpoint of the magnet, then which of the following statements is correct ?
a)
Magnet experiences a torque in clockwise direction
b)
Magnet experiences a torque in anticlockwise direction
c)
Magnet experiences a force, normal to the line of shortest distance
d)
Magnet experiences a force along the line of shortest distance
|
Geetika Shah answered |
There is a long straight wire W, the current flowing direction in the wire is into the plane of paper and the point of intersection on the axis of magnet is P.
If the midpoint of the bar magnet is P then the distance from the point P to the wire will be the shortest distance.
So, the bar magnet will experience a force along the line of shortest distance.
If the midpoint of the bar magnet is P then the distance from the point P to the wire will be the shortest distance.
So, the bar magnet will experience a force along the line of shortest distance.
Figure shown plane figure made of a conductor located in a magnetic field along the inward normal to the plane of the figure. The magnetic field starts diminishing. Then the induced current 
- a) At point P is clockwise
- b)At point Q is anticlockwise
- c)At point Q is clockwise
- d)At point R is zero
Correct answer is option 'A,C,D'. Can you explain this answer?
Figure shown plane figure made of a conductor located in a magnetic field along the inward normal to the plane of the figure. The magnetic field starts diminishing. Then the induced current
a)
At point P is clockwise
b)
At point Q is anticlockwise
c)
At point Q is clockwise
d)
At point R is zero
|
Divey Sethi answered |
As the field diminishes the current is induced in the coils such that if opposes the diminishing of the field. Hence, current is induced in clockwise directing in both the loops.
And as the loops are closed no current will come out of the loops and no current at point R.
Hence option A C D is the correct option.
In the given circuit the maximum deflection in the galvanometer occurs when
- a)magnet is rotated inside the coil
- b)magnet is stationary at the center of the coil.
- c)numbers of turns in the coil is reduced.
- d)magnet is pushed into the coil.
Correct answer is option 'D'. Can you explain this answer?
In the given circuit the maximum deflection in the galvanometer occurs when
a)
magnet is rotated inside the coil
b)
magnet is stationary at the center of the coil.
c)
numbers of turns in the coil is reduced.
d)
magnet is pushed into the coil.
|
sankalp raj answered |
This question based on lenz law. as the bar magnet is moving , there is a change in magnetic flux.This will give polarity in the coil. Hence the current developed in the coil. so the option d is right.
A constant current I is maintained in a solenoid. Which of the following quantities will not increase if an iron rod is inserted in the solenoid along its axis?- a)Magnetic field at the centre.
- b)Self-inductance of the solenoid.
- c)Magnetic flux linked with the solenoid.
- d)Rate of joule heating.
Correct answer is option 'D'. Can you explain this answer?
A constant current I is maintained in a solenoid. Which of the following quantities will not increase if an iron rod is inserted in the solenoid along its axis?
a)
Magnetic field at the centre.
b)
Self-inductance of the solenoid.
c)
Magnetic flux linked with the solenoid.
d)
Rate of joule heating.
|
Fahad Chauhan answered |
Magnetic field is directly proportional to permiability and when iron rod is inserted the relative permeability changes and thus magnetic field , self inductance is proportional to flux which is proportional to magnetic field and thus follow above explanation, and remaining last option rate of heating =I²R and both these factors doesn't get affected by iron rod , and hence this is correct option.
A coil of 100 turns is pulled in 0.04 sec. between the poles of a magnet, if its flux changes from 40 x 10-6 Wb per turn to 10-5 Wb per turn, then the average emf induced in the coil is- a)0.75V
- b)7.5V
- c)0.0075V
- d)0.075V
Correct answer is option 'D'. Can you explain this answer?
A coil of 100 turns is pulled in 0.04 sec. between the poles of a magnet, if its flux changes from 40 x 10-6 Wb per turn to 10-5 Wb per turn, then the average emf induced in the coil is
a)
0.75V
b)
7.5V
c)
0.0075V
d)
0.075V
|
|
Shalini Basu answered |
Given:
Number of turns, N = 100
Time taken, t = 0.04 sec
Initial flux per turn, Φ1 = 40 x 10^-6 Wb
Final flux per turn, Φ2 = 10^-5 Wb
To find: Average emf induced in the coil
Formula used:
The average emf induced in a coil is given by
E = ΔΦ/Δt
where ΔΦ is the change in magnetic flux and Δt is the time taken for the change.
Calculation:
Change in magnetic flux, ΔΦ = Φ2 - Φ1
= (10^-5 - 40 x 10^-6) Wb
= 6 x 10^-6 Wb
Time taken for the change, Δt = t/N
= 0.04/100 sec
= 4 x 10^-4 sec
Average emf induced in the coil, E = ΔΦ/Δt
= (6 x 10^-6)/(4 x 10^-4) V
= 0.075 V
Therefore, the average emf induced in the coil is 0.075 V, which is option D.
Number of turns, N = 100
Time taken, t = 0.04 sec
Initial flux per turn, Φ1 = 40 x 10^-6 Wb
Final flux per turn, Φ2 = 10^-5 Wb
To find: Average emf induced in the coil
Formula used:
The average emf induced in a coil is given by
E = ΔΦ/Δt
where ΔΦ is the change in magnetic flux and Δt is the time taken for the change.
Calculation:
Change in magnetic flux, ΔΦ = Φ2 - Φ1
= (10^-5 - 40 x 10^-6) Wb
= 6 x 10^-6 Wb
Time taken for the change, Δt = t/N
= 0.04/100 sec
= 4 x 10^-4 sec
Average emf induced in the coil, E = ΔΦ/Δt
= (6 x 10^-6)/(4 x 10^-4) V
= 0.075 V
Therefore, the average emf induced in the coil is 0.075 V, which is option D.
The magnetic flux linked with a coil is changed from 1 Wb to 0.1 Wb in 0.1 second. The induced emf is- a)0.9V
- b)0.09V
- c)9.0V
- d)0.009V
Correct answer is option 'C'. Can you explain this answer?
The magnetic flux linked with a coil is changed from 1 Wb to 0.1 Wb in 0.1 second. The induced emf is
a)
0.9V
b)
0.09V
c)
9.0V
d)
0.009V
|
|
Nikita Singh answered |
Change n in magnetic flux Δϕ=0.1−1=−0.9 Weber
Time taken Δt=0.1 sec
So, emf induced in the coil E=− Δϕ/Δt
⟹ E=− (−0.9)/ 0.1=9 Volts
Hence option C is the correct answer.
Time taken Δt=0.1 sec
So, emf induced in the coil E=− Δϕ/Δt
⟹ E=− (−0.9)/ 0.1=9 Volts
Hence option C is the correct answer.
A solenoid coil has 10 turns per cm along its length and a cross sectional area of 10 cm2. 100 turns of another wire are wound round the first solenoid coaxially. The two coils are electrically insulated from each other. The mutual inductance between the two coils is- a)0.13 mH
- b)1.30 mH
- c)0.013 mH
- d)13.0 mH
Correct answer is option 'A'. Can you explain this answer?
A solenoid coil has 10 turns per cm along its length and a cross sectional area of 10 cm2. 100 turns of another wire are wound round the first solenoid coaxially. The two coils are electrically insulated from each other. The mutual inductance between the two coils is
a)
0.13 mH
b)
1.30 mH
c)
0.013 mH
d)
13.0 mH
|
|
Geetika Shah answered |
n1=10 turns per cm, =1000 turns per metre
n2l=100, A=10 c=0.1 m2, M=μ0n1(n2l) A
=4πx10-7×1000×100×0.1H=0.13mh
n2l=100, A=10 c=0.1 m2, M=μ0n1(n2l) A
=4πx10-7×1000×100×0.1H=0.13mh
In Faraday’s experiment if the magnet is moved towards the coil, it results in ____________ in magnetic field B at any point on the wire loop. The _________ shows deflection. Thus emf is induced by changing B.- a)Decrease, galvanometer
- b)Increase, ammeter
- c)Increase, galvanometer
- d)Decrease, ammeter
Correct answer is option 'C'. Can you explain this answer?
In Faraday’s experiment if the magnet is moved towards the coil, it results in ____________ in magnetic field B at any point on the wire loop. The _________ shows deflection. Thus emf is induced by changing B.
a)
Decrease, galvanometer
b)
Increase, ammeter
c)
Increase, galvanometer
d)
Decrease, ammeter
|
Imk Pathsala answered |
Initailly the loop taken have no current or no magnetic field associated with it when the magnet moved towards the loop the galvanometer show deflection showing the presence of current and current moving in loop also has magnetic field around it
electromagnetic induction i.e currents can be induced in coils (Select the best)- a)Only if the coil moves
- b)Only if the coil moves and magnet also moves in the same direction
- c)if relative motion of coil and magnet is present.
- d)Only if the magnet moves
Correct answer is option 'C'. Can you explain this answer?
electromagnetic induction i.e currents can be induced in coils (Select the best)
a)
Only if the coil moves
b)
Only if the coil moves and magnet also moves in the same direction
c)
if relative motion of coil and magnet is present.
d)
Only if the magnet moves
|
Ezhil The Champ answered |
Consider a cylindrical copper coil connected serially to a galvanometer . a strong magnet with north or south pole is taken towards it. and coil is moved up and down.
when ever there is a relative motion between coil and the magnet the galvanometer shows deflection . indicating flow of induced current.
the deflection is momentary . it last so long as there is relative motion between coil and magnet.
the direction of induced current changes if magnet or coil is moved towards or away frm it
the deflection is more when the relative motion is faster or less when it is slow.
t
when ever there is a relative motion between coil and the magnet the galvanometer shows deflection . indicating flow of induced current.
the deflection is momentary . it last so long as there is relative motion between coil and magnet.
the direction of induced current changes if magnet or coil is moved towards or away frm it
the deflection is more when the relative motion is faster or less when it is slow.
t
A rectangular loop with a sliding connector of length l = 1.0 m is situated in a uniform magnetic field B = 2T perpendicular to the plane of loop. Resistance of connector is r = 2W. Two resistances of 6W and 3W are connected as shown in figure. Find the external force required to keep the connector moving with a constant velocity v = 2m/s. 
Correct answer is '2'. Can you explain this answer?
A rectangular loop with a sliding connector of length l = 1.0 m is situated in a uniform magnetic field B = 2T perpendicular to the plane of loop. Resistance of connector is r = 2W. Two resistances of 6W and 3W are connected as shown in figure. Find the external force required to keep the connector moving with a constant velocity v = 2m/s.
|
|
Sourav Kumar answered |
E=Bvl
e=(2) (2)(1)=4V
E=4V
r=2ohm
i= 4/2+2=1A
=Fm=ilB
= (1)(1)(2)
=2N (towards left)
=Therefore 2N
e=(2) (2)(1)=4V
E=4V
r=2ohm
i= 4/2+2=1A
=Fm=ilB
= (1)(1)(2)
=2N (towards left)
=Therefore 2N
A bar magnet is moved along the axis of copper ring placed far away from the magnet. Looking from the side of the magnet, an anticlockwise current is found to be induced in the ring. Which of the following may be true?- a)The south pole faces the ring and the magnet moves towards it.
- b)The north pole faces the ring and the magnet moves towards it.
- c)The south pole faces the ring and the magnet moves away from it.
- d)The north pole faces the ring and the magnet moves away from it.
Correct answer is option 'B,C'. Can you explain this answer?
A bar magnet is moved along the axis of copper ring placed far away from the magnet. Looking from the side of the magnet, an anticlockwise current is found to be induced in the ring. Which of the following may be true?
a)
The south pole faces the ring and the magnet moves towards it.
b)
The north pole faces the ring and the magnet moves towards it.
c)
The south pole faces the ring and the magnet moves away from it.
d)
The north pole faces the ring and the magnet moves away from it.
|
Ritika Sengupta answered |
When magnet is moving towards the ring, as the current flows in anti-clockwise direction when seen from magnet, a magnetic field directed towards the magnet from the ring is observed.
By Lenz's law this field is to oppose the movement of the magnet towards the ring.
Therefore the N-pole should be facing the ring, as only then will the induced field by the ring will oppose the movement of the approaching magnet.
Therefore, the north pole faces the ring and the magnet moves towards it and the south pole faces the ring and the magnet moves away from it.
By Lenz's law this field is to oppose the movement of the magnet towards the ring.
Therefore the N-pole should be facing the ring, as only then will the induced field by the ring will oppose the movement of the approaching magnet.
Therefore, the north pole faces the ring and the magnet moves towards it and the south pole faces the ring and the magnet moves away from it.
If we take the analogy between mechanical motion and electric circuits, then inductance is analogous to- a)Torque
- b)Force
- c)Momentum
- d)Moment of Inertia
Correct answer is option 'D'. Can you explain this answer?
If we take the analogy between mechanical motion and electric circuits, then inductance is analogous to
a)
Torque
b)
Force
c)
Momentum
d)
Moment of Inertia
|
|
Preeti Iyer answered |
Inductance in electric circuits plays the same role as moment of inertia in mechanical circuits.
Two similar circular co-axial loops carry equal current in the same direction. If the loops be brought nearer, the currents in them will- a)Change direction
- b)Decrease
- c)Increase
- d)Remain same
Correct answer is option 'B'. Can you explain this answer?
Two similar circular co-axial loops carry equal current in the same direction. If the loops be brought nearer, the currents in them will
a)
Change direction
b)
Decrease
c)
Increase
d)
Remain same
|
|
Rohit Shah answered |
The answer is B. Its Faraday's law of magnetic induction. As the loops are brought closer to each other, the magnetic field from one loop to another increases, increasing the flux. The loops will want to counter this increase in flux, creating a back EMF that will oppose the original current. This reduces the current in each loop.
The total number of magnetic lines of force crossing a surface normally is termed as- a)Magnetic field.
- b)Magnetic permeability.
- c)Magnetic flux.
- d)Magnetic susceptibility.
Correct answer is option 'C'. Can you explain this answer?
The total number of magnetic lines of force crossing a surface normally is termed as
a)
Magnetic field.
b)
Magnetic permeability.
c)
Magnetic flux.
d)
Magnetic susceptibility.
|
Nabanita Pillai answered |
The measurement of the total magnetic field that passes through a given area is known as magnetic flux. It is helpful in describing the effects of the magnetic force on something occupying a given area.
If we consider a simple flat area A as our example and angle θ as the angle between the normal to the surface and a magnetic field vector, then the magnetic flux is given by the equation:
ϕ=BAcosΘ
If we consider a simple flat area A as our example and angle θ as the angle between the normal to the surface and a magnetic field vector, then the magnetic flux is given by the equation:
ϕ=BAcosΘ
A magnet is moved towards the coil (i) quickly, (ii) slowly, the induced emf is- a)more in (i) than in (ii) case.
- b)Smaller in (i) than in (ii) case.
- c)Same in both.
- d)Nothing can be said.
Correct answer is option 'A'. Can you explain this answer?
A magnet is moved towards the coil (i) quickly, (ii) slowly, the induced emf is
a)
more in (i) than in (ii) case.
b)
Smaller in (i) than in (ii) case.
c)
Same in both.
d)
Nothing can be said.
|
|
Rajesh Gupta answered |
When a magnet is moved towards the coil quickly, the rate of change of flux is larger than that if the magnetic field is moved slowly, thus larger emf is induced due to quick movement of the coil.
Why is the iron core of a transformer made laminated instead of being in one solid piece?- a)To reduce the magnetic field link losses
- b)To reduce the loss due to heating of coils
- c)To reduce the hysterisis losses
- d)To reduce the losses due to eddy currents.
Correct answer is option 'D'. Can you explain this answer?
Why is the iron core of a transformer made laminated instead of being in one solid piece?
a)
To reduce the magnetic field link losses
b)
To reduce the loss due to heating of coils
c)
To reduce the hysterisis losses
d)
To reduce the losses due to eddy currents.
|
Mira Sharma answered |
The laminated iron core prevents the formation of eddy currents and thus reduces the loss of energy.
Foucault Currents are also calleda)Both eddy and induced currentb)Direct Currentsc)Induced Currentd)Eddy CurrentsCorrect answer is option 'D'. Can you explain this answer?
|
|
Nandini Patel answered |
Eddy currents are the currents which are induced in a conductor whenever the amount of linked magnetic flux with the conductor changes. These were discovered by Foucault in the year 1895 and hence they are also called Foucault currents.
Chapter doubts & questions for Electromagnetic Induction - Physics for JEE Main & Advanced 2025 is part of JEE exam preparation. The chapters have been prepared according to the JEE exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for JEE 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
Chapter doubts & questions of Electromagnetic Induction - Physics for JEE Main & Advanced in English & Hindi are available as part of JEE exam.
Download more important topics, notes, lectures and mock test series for JEE Exam by signing up for free.
Physics for JEE Main & Advanced
268 videos|756 docs|171 tests
|
|
© EduRev
|
Education Revolution
|
|
Signup to see your scores
go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup