JEE Main · 2020 · 08 Jan 2020 · Shift 1 · Electromagnetic Induction

At time

t = 0

magnetic field of 1000 Gauss is passing perpendicularly through the area defined by the closed loop shown in the figure. If the magnetic field reduces linearly to 500 Gauss, in the next 5s, then induced EMF in the loops is:

(A) $28 μ V$
(B) $56 μ V$ ✓ Correct
(C) $48 μ V$
(D) $36 μ V$

Answer: (B)

Solution

By Faraday's law the magnitude of the induced emf is

ε = A ∣ d B / d t ∣

. From the figure the loop's effective area is

16 \times 4 - 4 \times 2 = 56 cm^{2} = 56 \times 1 0^{- 4} m^{2}

. The field falls from

1000

G to

500

G in

5

s, so

∣ d B / d t ∣ = \frac{500}{5} \times 1 0^{- 4} = 100 \times 1 0^{- 4}

T/s. Hence

ε = 56 \times 1 0^{- 4} \times 100 \times 1 0^{- 4} = 56 \times 1 0^{- 6}

V, that is

56 μ V

JEE Main · 2020 · 08 Jan 2020 · Shift 1 · Single correct option

Practise more: all JEE Main PYQs on Electromagnetic Induction →

More JEE Main questions on Electromagnetic Induction

XPQY is a vertical smooth long loop having a total resistance R where PX is parallel to QY and separation between them is $l$ . A constant magnetic field B perpendicular to the plane of the loop exists in the entire space. A rod CD of length L ( $L > l$ ) and mass $m$ is made to sli …
JEE Main 2026View solution →
Three identical coils $C_{1}, C_{2}$ and $C_{3}$ are closely placed such that they share a common axis. $C_{2}$ is exactly midway. $C_{1}$ carries current $I$ in anti-clockwise direction while $C_{3}$ carries curre …
JEE Main 2026View solution →
Inductance of a coil with $1 0^{4}$ turns is 10 mH and it is connected to a dc source of 10 V with internal resistance of $10Ω$ . The energy density in the inductor when the current reaches $(\frac{1}{e})$ of its maximum value is …
JEE Main 2026View solution →
Figure shows the circuit that contains three resistances ( $9Ω$ each) and two inductors (4 mH each). The reading of ammeter at the moment switch $K$ is turned ON, is ______ A.
JEE Main 2026View solution →
A conducting circular loop is rotated about its diameter at a constant angular speed of $100 rad / s$ in a magnetic field of 0.5 T perpendicular to the axis of rotation. When the loop is rotated by $3 0^{\circ}$ from the horizontal position, the induced EMF is 15 …
JEE Main 2026View solution →
A capacitor C is first charged fully with potential difference of $V_{0}$ and disconnected from the battery. The charged capacitor is connected across an inductor having inductance L . In t s $25%$ of the initial energy in the capacitor is transferred to the induct …
JEE Main 2026View solution →