Question

Assertion (A): Skin depth is the depth by which electromagnetic wave is attenuated to $1/e$ of its original value. Reason (R): Depth of penetration decreases with increasing wavelength.

• A. Both (A) and (R) are correct and (R) is correct explanation
• B. Both (A) and (R) are correct but (R) is not explanation
• C. (A) is correct but (R) is incorrect
• D. (A) is incorrect but (R) is correct

Hint:

Higher frequency → smaller skin depth.

Answer 1

The Correct Option is C

Concept: Skin depth: \[ \delta = \sqrt{\frac{2}{\omega \mu \sigma}} \]

Step 1: Assertion Definition of skin depth is correct. \[ \Rightarrow \text{A is TRUE} \]

Step 2: Reason \[ \delta \propto \frac{1}{\sqrt{f}} \] Higher frequency → lower depth But wavelength inversely relates to frequency. Thus statement incorrect. \[ \Rightarrow \text{R is FALSE} \] \[ \therefore \text{Correct answer is (C)} \]