Question

In the arrangement shown in given figure current from $A$ to $B$ is increasing in magnitude. Induced current in the loop will

• A. have clockwise direction
• B. have anticlockwise direction
• C. be zero
• D. oscillate between clockwise and anticlockwise

Answer 1

The correct option is A have clockwise direction

As the current is increasing, the magnetic field due to straight wire is also increasing. The flux through the loop is outwards and increasing. We have,
$ϵ=-\frac{d\varphi }{dt}$
As $\frac{d}{dt}$ is +ve as $\varphi$ is increasing, $\varphi$ is +ve as it is outwards $ϵ$ is negative
Since $ϵ$ is -ve the current must flow clockwise.

OR

According to Lenz’s law generated current flows always in such a direction as to oppose the change which is giving rise to it.
As the current is increasing, the magnetic field due to straight wire is also increasing. The flux through the loop is outwards and increasing. Flux due to generated current should be inwards, So direction of current flow should be clockwise.