A planar loop of wire rotates in a uniform magnetic field. Initially, at , the plane of the loop is perpendicular to the magnetic field. If it rotates with a period of 10 s about an axis in its plane then the magnitude of induced emf will be maximum and minimum, respectively at:
- (A)2.5 s and 5.0 s✓ Correct
- (B)5.0 s and 10.0 s
- (C)2.5 s and 7.5 s
- (D)5.0 and 7.5 s
Answer: (A)
Solution
With the loop starting face-on to the field, the flux is where rad/s. The induced emf is . This is largest when the sine reaches , first at , i.e. s, and it falls to zero when the sine vanishes, the first such non-trivial instant being s.
JEE Main · 2020 · 07 Jan 2020 · Shift 2 · Single correct option