A square loop of side 15 cm being moved towards right at a constant speed of 2cm/s as shown in figure. The front edge enters the 50 cm wide magnetic field at t=0. The value of induced emf in the loop at t=10s will be :
(A)0.3 mV
(B)4.5 mV
(C)zero✓ Correct
(D)3 mV
Answer: (C)
Solution
The loop takes 50/2=25 s to fully enter the 50 cm wide field, so by t=10 s the leading edge has moved 2×10=20 cm — the loop (15 cm side) is already completely inside the field (since 20 cm>15 cm, the trailing edge entered at t=7.5 s).
Once the loop is entirely inside a uniform field, the flux through it is constant, so
ε=−dtdϕ=0
JEE Main · 2024 · 09 Apr 2024 · Shift 2 · Single correct option