Electromagnetic Induction NEET Previous Year Questions with Answers

Q 1 :
AB is a part of an electrical circuit (see figure). The potential difference $'' V_{A} - V_{B}'',$ at the instant when current $i = 2 A$ and is increasing at a rate of 1 amp/second is [2025]

[IMAGE 250]

9 volt
10 volt
5 volt
6 volt

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4

(2)

[IMAGE 251]

From the diagram (Using KVL)

$V_{A} - L \frac{d i}{d t} - 5 - 2 i = V_{B}$

Using, $i = 2 A, \frac{d i}{d t} = 1$ $A/sec$ and $L = 1$ $H,$ we get

$V_{A} - 1 - 5 - 4 = V_{B} \Rightarrow V_{A} - V_{B} = 10$ $V$

Q 2 :
Let us consider two solenoids $A$ and $B,$ made from same magnetic material of relative permeability $μ_{r}$ and equal area of cross-section. Length of $A$ is twice that of $B$ and the number of turns per unit length in $A$ is half that of $B .$ The ratio of self inductances of the two solenoids, $L_{A} : L_{B}$ is [2024]

1 : 2
2 : 1
8 : 1
1 : 8

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(1)

Self inductance of solenoid,

$L = \frac{μ_{0} N^{2} A}{l} = μ_{r} μ_{0} n^{2} l A$

Where, $n$ is number of turns per unit length,

$A =$ Area and, $l =$ length

Given: $l_{A} = 2 l_{B}, n_{A} = \frac{1}{2} n_{B}$

$∴$ $\frac{L_{A}}{L_{B}} = \frac{μ_{r} μ_{0} l_{A} A_{A} n_{A}^{2}}{μ_{r} μ_{0} l_{B} A_{B} n_{B}^{2}} = 2 l_{B} \cdot \frac{n_{B}^{2}}{4 n_{B}^{2} l_{B}} = \frac{1}{2}$ $(∵ A_{A} = A_{B})$

Q 3 :
The amplitude of the charge oscillating in a circuit decreases exponentially as $Q = Q_{0} e^{- R t / 2 L},$ where $Q_{0}$ is the charge at $t = 0$ $s.$ The time at which charge amplitude decreases to $0.50$ $Q_{0}$ is nearly

[Given that $R = 1.5 Ω, L = 12$ $mH, \ln (2) = 0.693$ ] [2024]

19.01 ms
11.09 ms
19.01 s
11.09 s

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4

(2)

Given, $R = 1.5 Ω$

$L = 12$ $mH; \ln$ $2 = 0.693$

At $t = 0, Q = Q_{0} e^{- R t / 2 L}$ ...(i)

At $t = t_{1}, Q = 0.50$ $Q_{0}$ ...(ii)

$0.50$ $Q = Q_{0} e^{- R t_{1} / 2 L}$

$\frac{1}{2} = e^{- R t_{1} / 2 L} or 2 = e^{R t_{1} / 2 L}$

Taking log of both sides, $\ln 2 = \frac{R t_{1}}{2 L} or 0.693 = \frac{1.5 t}{24 mH}$

$∴$ $t_{1} = 11.09$ $ms$

Q 4 :
The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is [2023]

8 mJ
8 μJ
4 μJ
4 mJ

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(2)

As, $U = \frac{1}{2} L I^{2} = \frac{1}{2} \times 4 \times 10^{- 6} \times 2 \times 2; U = 8 μ J$

Q 5 :
Two conducting circular loops of radii $R_{1}$ and $R_{2}$ are placed in the same plane with their centres coinciding. If $R_{1} ≫ R_{2}$ , the mutual inductance $M$ between them will be directly proportional to [2021]

$\frac{R_{2}^{2}}{R_{1}}$
$\frac{R_{1}}{R_{2}}$
$\frac{R_{2}}{R_{1}}$
$\frac{R_{1}^{2}}{R_{2}}$

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4

(1)

Let a current $I_{1}$ flows through the outer circular coil of radius $R_{1} .$

The magnitude field at the centre of the coil is $B_{1} = \frac{μ_{0} I_{1}}{2 R_{1}}$

As the inner coil of radius $R_{2}$ is placed coaxially, therefore, $B_{1}$ may be taken constant over its cross-sectional area.
Hence, flux associated with the inner coil is

$ϕ_{2} = B_{1} π R_{2}^{2} = \frac{μ_{0} I_{1}}{2 R_{1}} π R_{2}^{2} \Rightarrow$ As $M = \frac{ϕ_{2}}{I_{1}} = \frac{μ_{0} π R_{2}^{2}}{2 R_{1}} ∴ M \propto \frac{R_{2}^{2}}{R_{1}}$

Q 6 :
The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance [2018]

0.138 H
138.88 H
1.389 H
13.89 H

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(4)

Magnetic potential energy stored in an inductor is given by

$U = \frac{1}{2} L I^{2} \Rightarrow 25 \times 10^{- 3} = \frac{1}{2} \times L \times {(60 \times 10^{- 3})}^{2}$

$L = \frac{25 \times 2 \times 10^{6} \times 10^{- 3}}{3600} = 13.89$ $H$

Topic Question Set

Q 1 :
AB is a part of an electrical circuit (see figure). The potential difference $'' V_{A} - V_{B}'',$ at the instant when current $i = 2 A$ and is increasing at a rate of 1 amp/second is [2025]

[IMAGE 250]

Q 3 :
The amplitude of the charge oscillating in a circuit decreases exponentially as $Q = Q_{0} e^{- R t / 2 L},$ where $Q_{0}$ is the charge at $t = 0$ $s.$ The time at which charge amplitude decreases to $0.50$ $Q_{0}$ is nearly

[Given that $R = 1.5 Ω, L = 12$ $mH, \ln (2) = 0.693$ ] [2024]

Q 4 :
The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is [2023]

Q 5 :
Two conducting circular loops of radii $R_{1}$ and $R_{2}$ are placed in the same plane with their centres coinciding. If $R_{1} ≫ R_{2}$ , the mutual inductance $M$ between them will be directly proportional to [2021]

Q 6 :
The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance [2018]

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Topic Question Set

Q 1 : AB is a part of an electrical circuit (see figure). The potential difference ''VA-VB'', at the instant when current i=2A and is increasing at a rate of 1 amp/second is [2025] [IMAGE 250]

Q 3 : The amplitude of the charge oscillating in a circuit decreases exponentially as Q=Q0e-Rt/2L, where Q0 is the charge at t=0s. The time at which charge amplitude decreases to 0.50 Q0 is nearly [Given that R=1.5Ω, L=12 mH, ln(2)=0.693] [2024]

Q 4 : The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is [2023]

Q 5 : Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1≫R2, the mutual inductance M between them will be directly proportional to [2021]

Q 6 : The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance [2018]

Want Us to Email you About Special Offers & Updates?

Q 1 :
AB is a part of an electrical circuit (see figure). The potential difference $'' V_{A} - V_{B}'',$ at the instant when current $i = 2 A$ and is increasing at a rate of 1 amp/second is [2025]

[IMAGE 250]

Q 3 :
The amplitude of the charge oscillating in a circuit decreases exponentially as $Q = Q_{0} e^{- R t / 2 L},$ where $Q_{0}$ is the charge at $t = 0$ $s.$ The time at which charge amplitude decreases to $0.50$ $Q_{0}$ is nearly

[Given that $R = 1.5 Ω, L = 12$ $mH, \ln (2) = 0.693$ ] [2024]

Q 4 :
The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is [2023]

Q 5 :
Two conducting circular loops of radii $R_{1}$ and $R_{2}$ are placed in the same plane with their centres coinciding. If $R_{1} ≫ R_{2}$ , the mutual inductance $M$ between them will be directly proportional to [2021]

Q 6 :
The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance [2018]