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JEE Main 2025 January Physics: Electromagnetic Induction & Alternating Current – Previous Year Questions

All 11 questions asked from Electromagnetic Induction & Alternating Current in JEE Main 2025 January Physics (22, 23, 24, 28 and 29 January, all shifts). This chapter is about 4.4% of the 250 Physics questions in the session: 8 single-correct (MCQ) and 3 numerical-value questions. Select an answer to attempt each question, and open “View solution” under it.

11questions
8MCQ
3numerical
4.4%of Physics paper

Topics asked in this chapter

  • Alternating Current – 4 questions
  • Electromagnetic Induction – 7 questions

Alternating Current

Q122 Jan 2025 · Shift 2MCQ
A series LCR circuit is connected to an alternating source of emf $E$. The current amplitude at resonant frequency is $I_0$. If the value of resistance $R$ becomes twice of its initial value then amplitude of current at resonance will be
  1. A
    $2I_0$
  2. B
    $I_0$
  3. C
    $\frac{I_0}{\sqrt{2}}$
  4. D
    $\frac{I_0}{2}$
Q223 Jan 2025 · Shift 2Numerical
In a series LCR circuit, a resistor of 300 $\Omega$, a capacitor of 25 nF and an inductor of 100 mH are used. For maximum current in the circuit, the angular frequency of the ac source is $\times 10^{4}$ radians s$^{-1}$.
Q324 Jan 2025 · Shift 1MCQ
An alternating current is given by $I = I_A \sin\omega t + I_B \cos\omega t$. The r.m.s. current will be
  1. A
    $\sqrt{\dfrac{I_A^2+I_B^2}{2}}$
  2. B
    $\dfrac{\sqrt{I_A^2+I_B^2}}{2}$
  3. C
    $\dfrac{|I_A+I_B|}{\sqrt{2}}$
  4. D
    $\sqrt{I_A^2+I_B^2}$
Q429 Jan 2025 · Shift 1MCQ
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Choke coil is simply a coil having a large inductance but a small resistance. Choke coils are used with fluorescent mercury-tube fittings. If household electric power is directly connected to a mercury tube, the tube will be damaged.
Reason (R) : By using the choke coil, the voltage across the tube is reduced by a factor $\left(R/\sqrt{R^2+\omega^2L^2}\right)$, where $\omega$ is frequency of the supply across resistor $R$ and inductor $L$. If the choke coil were not used, the voltage across the resistor would be the same as the applied voltage.
In the light of the above statements, choose the most appropriate answer from the options given below :
  1. A
    Both (A) and (R) are true but (R) is not the correct explanation of (A)
  2. B
    Both (A) and (R) are true and (R) is the correct explanation of (A)
  3. C
    (A) is false but (R) is true
  4. D
    (A) is true but (R) is false

Electromagnetic Induction

Q522 Jan 2025 · Shift 2MCQ
A rectangular metallic loop is moving out of a uniform magnetic field region to a field free region with a constant speed. When the loop is partially inside the magnetic field, the plot of magnitude of induced emf ($\varepsilon$) with time ($t$) is given by
  1. A
    Figure for the question
  2. B
    Figure for the question
  3. C
    Figure for the question
  4. D
    Figure for the question
Q623 Jan 2025 · Shift 1MCQ
Regarding self-inductance:
A. The self-inductance of the coil depends on its geometry.
B. Self-inductance does not depend on the permeability of the medium.
C. Self-induced e.m.f. opposes any change in the current in a circuit.
D. Self-inductance is electromagnetic analogue of mass in mechanics.
E. Work needs to be done against self-induced e.m.f. in establishing the current.
Choose the correct answer from the options given below:
  1. A
    B, C, D, E only
  2. B
    A, C, D, E only
  3. C
    A, B, C, D only
  4. D
    A, B, C, E only
Q723 Jan 2025 · Shift 1Numerical
In the given circuit the sliding contact is pulled outwards such that electric current in the circuit changes at the rate of 8 A/s. At an instant when $R$ is 12 $\Omega$, the value of the current will be A.
Figure for the question
Q828 Jan 2025 · Shift 2MCQ
A uniform magnetic field of 0.4 T acts perpendicular to a circular copper disc 20 cm in radius. The disc is having a uniform angular velocity of $10\pi$ rad s$^{-1}$ about an axis through its centre and perpendicular to the disc. What is the potential difference developed between the axis of the disc and the rim ? ($\pi = 3.14$)
  1. A
    0.0628 V
  2. B
    0.1256 V
  3. C
    0.5024 V
  4. D
    0.2512 V
Q928 Jan 2025 · Shift 2Numerical
A conducting bar moves on two conducting rails as shown in the figure. A constant magnetic field $B$ exists into the page. The bar starts to move from the vertex at time $t=0$ with a constant velocity. If the induced EMF is $E \propto t^{n}$, then value of $n$ is .
Figure for the question
Q1029 Jan 2025 · Shift 1MCQ
Consider $I_1$ and $I_2$ are the currents flowing simultaneously in two nearby coils 1 & 2, respectively. If $L_1$ = self inductance of coil 1, $M_{12}$ = mutual inductance of coil 1 with respect to coil 2, then the value of induced emf in coil 1 will be
  1. A
    $\varepsilon_1 = -L_1\frac{dI_1}{dt} + M_{12}\frac{dI_2}{dt}$
  2. B
    $\varepsilon_1 = -L_1\frac{dI_1}{dt} - M_{12}\frac{dI_2}{dt}$
  3. C
    $\varepsilon_1 = -L_1\frac{dI_1}{dt} - M_{12}\frac{dI_1}{dt}$
  4. D
    $\varepsilon_1 = -L_1\frac{dI_2}{dt} - M_{12}\frac{dI_1}{dt}$
Q1129 Jan 2025 · Shift 1MCQ
A coil of area $A$ and $N$ turns is rotating with angular velocity $\omega$ in a uniform magnetic field $\vec{B}$ about an axis perpendicular to $\vec{B}$. Magnetic flux $\varphi$ and induced emf $\varepsilon$ across it, at an instant when $\vec{B}$ is parallel to the plane of coil, are :
  1. A
    $\varphi = AB,\ \varepsilon = 0$
  2. B
    $\varphi = 0,\ \varepsilon = 0$
  3. C
    $\varphi = 0,\ \varepsilon = NAB\omega$
  4. D
    $\varphi = AB,\ \varepsilon = NAB\omega$
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