Question

Assertion :In very fast-changing fields, the magnetic field does not penetrate completely into the interior of the material. Reason: It takes time for electrons to be in equilibrium due to the application of electric field.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Assertion is correct sue to skin effect.The penetration depth for a good conductor can be calculated from the following equation.

$S=\frac{1}{\sqrt{\pi f\mu \sigma }}$ where S = penetration depth (m)

f= frequency (Hz), $\mu$ = magnetic permeability (H/m) , $\sigma$ = conductivity of material (S/m).

For very fast changing magnetic field (f) is very large. S$\to$ O

reason is correct $\to$ eddy current flow perpendicular to the magnetic field within the conductor.Edgy current flow to opposite the external field. No relation between assertion and reason.