Question

Assertion $\left(A\right)$: The induced e.m.f. and current will be same in two identical loops of copper and aluminium when rotated with same speed in the same magnetic field.

Reason $\left(R\right)$: Induced e.m.f. is proportional to rate of change of magnetic field while induced current depends on resistance of wire.

• A. Both $\left(A\right)$ and $\left(R\right)$ are true, and $\left(R\right)$ is the correct explanation of $\left(A\right)$
• B. Both $\left(A\right)$ and $\left(R\right)$ are true, but $\left(R\right)$ is not the correct explanation of $\left(A\right)$
• C. $\left(A\right)$ is true but $\left(R\right)$ is false
• D. $\left(A\right)$ is false but $\left(R\right)$ is true

Answer 1

The correct option is D $\left(A\right)$ is false but $\left(R\right)$ is true

As we know, induced e.m.f. $e=-\frac{d\varphi }{dt}$

Flux linkage with a coil is independent of the material. So emf will be same as the loops are identical in shape.

But induced current

$i_{ind}=\frac{(-\frac{d\varphi }{dt})}{R}=\frac{e}{R}$

And $R=\frac{\rho l}{A}$ [it depends on the property of the material.]

Hence, induced current will depend upon the material because Resistivity $\left(\rho \right)$ is material dependent.

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(D\right)$ is the correct answer.