STANDARDPhysics-Electromagnetic Induction
STANDARD Physics Motional EMF MCQ Question
Type: MCQ-conceptual-Medium-Class 12
A conducting circular loop is placed in a uniform magnetic field, B = 0.025 T with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of 1 mm s⁻¹. The induced emf when the radius is 2 cm, is
A
2π μV
B
μV
C
π/2 μV
D
2 μV
Correct Answer
Option A
Detailed Explanation
The emf induced in a shrinking loop is given by ε = -d(BA)/dt. Here, A = πr² and dr/dt = -1 mm/s = -0.001 m/s. Thus, ε = B × 2πr × dr/dt = 0.025 × 2π × 0.02 × (-0.001) = -2π μV.
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