A conducting loop of radius 10 √π cm is placed perpendicular to a uniform magnetic field of 0.5T. The magnetic field is decreased to zero in 0.5s at…
JEE Main 2023 — Physics Electromagnetism
2023mcqmedium
A conducting loop of radius π10cm is placed perpendicular to a uniform magnetic field of 0.5T. The magnetic field is decreased to zero in 0.5s at a steady rate. The induced emf in the circular loop at 0.25s is:
Official previous-year question
Held on 24 Jan 2023 · Verified 6 Jul 2026.
Options
A
emf=1mV
B
emf=10mV
C
emf=100mV
D
emf=5mV
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Solution
Given: B=0.5T\text{at}t=0&B=0, at t=0.5s.
Magnetic field will decrease linearly as given below. We can say, value of magnetic field at t=0.25will beB=0.25.
Therefore,
ϵind =∣ΔtΔϕ∣=∣ΔtΔ(BA)∣=A∣ΔtΔ(B)∣
=π×(π10)2×10−4×(0.250.25)
=10−2×1
=0.01V=10mV
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