Question

Whenever a magnet is moved either towards or away from a conducting coil, an emf is induced, the magnitude of which is independent of

• A. the strength of the magnetic field
• B. the speed with which the magnet is moved
• C. the number of tums in the coil
• D. the resistance of the coil

Answer 1

The correct option is D the resistance of the coil

The magnitude of the induced emfin a coil when a magnet is moved either towards or away from it is given by
$e=-N\frac{d\varphi }{dt}$ or $e=-N\frac{d\left(BA\right)}{dt}$
From above expression, it is clear that e depends on

1. the strength of the field (B)
2. the number of turns in the coil (N)
3. the area ofcross-section ofthe coil (A) and(iv) the time-interval (dt) which depends on the velocity (v) with which the magnet is moved.

Hence, the induced emf doesn't depend on the resistance of the coil.