Question

A coil and a magnet moves with their constant speeds $5m/sec$ and $3m/sec$ respectively, towards each other, then induced emf in coil is $16mV$. If both moves in the same direction, then induced emf in the coil:

• A. $15mV$
• B. $4mV$
• C. $64mV$
• D. $zero$

Answer 1

The correct option is D $zero$

When both coil and magnet moves in same direction, then there will be no induced emf in the coil because there is no change in the magnetic flux. If both are moves in same direction, then induced emf in coil is zero. The induced emf is given by:

$emf=\frac{-d\varphi }{dt}=\frac{-d\left(BA\right)}{dt}$