Question

The variation of induced emf $\left(e\right)$ with time $\left(t\right)$ in a coil if a short bar magnet is moved along its axis with a constant velocity is best represented as

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

According to Faraday's law of induction,

$e=\text{induced emf}=-\frac{d\varphi }{dt}$

When the magnet is moving towards the coil, then the magnetic flux associated with it increases. Similarly, when the magnet moves away from the coil, the magnetic flux associated with it starts decreasing.

So, the polarity of induced emf will be opposite in the two cases while entering and while leaving the coil which is happening in option $\left(\text{B}\right)$ only.

Hence, option $\left(\text{B}\right)$ is the right choice.