Question

A short bar magnet is moved with constant velocity along the axis of a short coil. The magnet enters into the coil and then leaves it. The variation of induced emf $\left(\epsilon \right)$ with time $\left(t\right)$ is best represented as

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

$\Rightarrow$As per Lenz's law the emf will be induced such that, induced current's direction will produce a magnetic field $\left(B\right)$, which opposes the $\left(B\right)$ due to bar magnet.

$\therefore$In both cases induced emf will be of opposite sign,since flux through coil $(\varphi \uparrow )$ when magnet approaches it and $(\varphi \downarrow )$ when bar magnet goes past the coil.
$\Rightarrow \left(b\right)$ option is correct, because it shows change in sign of emf.