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Suppose a long rectangular loop of width $w$ is moving along the $x$ -direction with its left arm in magnetic field perpendicular to the plane of the loop (see figure). The resistance of the loop is zero and it has an inductance $L .$ At time, $t = 0,$ its left arm passes the origin, $O .$

If for $t \geq 0,$ the current in the loop is $I$ and the distance of its left arm from the origin is $x,$ then $I$ versus $x$ graph will be:

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Important Questions on Electromagnetic Induction

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

The self induced emf of a coil is

25

volts. When the current in it is changed at uniform rate from

10 A

25 A

1 s

, the change in the energy of the inductance is:

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

A series

L - R

circuit is connected to a battery of emf

V

. If the circuit is switched on at

t = 0

, then the time at which the energy stored in the inductor reaches

(\frac{1}{n})

times of its maximum value, is :

HARD

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

The inductors of two $L R$ circuits are placed next to each other, as shown in the figure. The values of the self-inductance of the inductors, resistances, mutual-inductance and applied voltages are specified in the given circuit. After both the switches are closed simultaneously, the total work done by the batteries against the induced $E M F$ in the inductors by the time the currents reach their steady-state values is_______ $mJ$ .

Question Image

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

The average emf induced in a coil, when the current in it changes from

2 A

4 A

0.05 s

, is

8 V

. Find the self-inductance of this coil.

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

A long solenoid has

500

turns. When a current of

2 A

is passed through it, the resulting magnetic flux linked with each turn of the solenoid is

4 \times 10^{- 3} Wb

, then self-inductance of the solenoid is

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

In an inductor of self-inductance

L = 2 mH

, current changes with time according to relation

i = t^{2} e^{- 1}

. At what time

e m f

is zero?

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

Two concentric circular coils,

C_{1}

and

C_{2}

, are placed in the

X Y

plane.

C_{1}

has

500

turns, and a radius of

1 cm

C_{2}

has 200 turns and radius of

20 cm . C_{2}

carries a time dependent current

I (t) = (5 t^{2} - 2 t + 3) A

where

t

is in s. The emf induced in

C_{1} (in mV)

at the instant

t = 1

s is

\frac{4}{x} .

The value of

x

is ..........

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

N

is the number of turns in a circular coil, the value of its self inductance varies as

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

In a fluorescent lamp choke (a small transformer)

100 V

of reverse voltage is produced when the choke current changes uniformly from

0 .25 A

0

in a duration of

0 .025 ms

. The self-inductance of the choke (in

mH

) is estimated to be ________

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

The total number of turns and cross-section area in a solenoid is fixed. However, its length

L

is varied by adjusting the separation between windings. The inductance of solenoid will be proportional to:

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

Consider two coils of radii $r_{1}$ and $r_{2}$ , placed at a distance $d$ away as shown in the figure. Assuming the length of the coils $l_{1}, l_{2} ≫ d$ with $n_{1}, n_{2}$ the number of turns per unit length of the two coils respectively, the mutual inductance of the two coils is

Question Image

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

The primary and the secondary coils of a transformer contains

10

and

100

turns

respectively. The primary coil is connected to a battery that supplies a constant voltage of

1.5 V

. The voltage across the secondary coil is

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

Two coaxial coils

A

and

B

of radii

R_{1}

and

R_{2}

are placed in the same plane.

(R_{2} > R_{1})

. If a current is passed through coil

B

, the coefficient of mutual inductance between the coils is proportional to

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

Two inductors $L_{1}$ and $L_{2}$ are connected in parallel and a time varying current flows as shown in figure. The ratio ot current $\frac{i_{1}}{i_{2}}$ at any ime $t$ Is Question Image

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

A toroidal solenoid with air core has an average radius

R

number of turns

N

and area of cross-section

A

. The self-inductance of the solenoid is (Neglect the field variation across the cross-section of the toroid)

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

Two different coils have self-inductance

L_{1} = 9 mH

and

L_{2} = 3 mH

. At a certain instant, the current in the two coils is increasing at the same rate and the power supplied to the coils is also the same. The ratio of the energy stored in the two coils

(\frac{U_{1}}{U_{2}})

at that instant is

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

Consider a conducting wire of length

L

bent in the form of a circle of radius

R

and another conductor of length

a (a < < R)

is bent in the form of a square. The two loops are then placed in same plane such that the square loop is exactly at the centre of the circular loop. What will be the mutual inductance between the two loops?

MEDIUM

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

Two coils

' P'

and

' Q'

are separated by some distance. When a current of

3 A

flows through coil

' P^{'},

a magnetic flux of

10^{- 3} W b

passes through

' Q^{'} .

No current is passed through

' Q^{'} .

When no current passes through

' P'

and a current of

2 A

passes through

' Q^{'},

the flux through

' P'

is:

HARD

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

A small circular loop of wire of radius

a

is located at the centre of a much larger circular wire loop of radius

b

. The two loops are in the same plane. The outer loop of radius

b

carries an alternating current

I = I_{0} \cos (ω t) .

The emf induced in the smaller inner loop is nearly:

EASY

Physics>Electricity and Magnetism>Electromagnetic Induction>Self and Mutual Induction

A long solenoid has

1000

turns. When a current of

4 A

flows through it the magnetic flux linked with each turn of the solenoid is

4 \times 10^{- 3} Wb.

The self-inductance of the solenoid is:

Important Questions on Electromagnetic Induction

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