Topic: Electromagnetics
If frequency is decreased 4 times, then skin depth of an Electromagnetic wave inside a conductor will be
- A. halved
- B. quadrupled
- C. doubled
- D. no change
Answer: C. doubled
Explanation: Skin depth is given by $\delta = \frac{1}{\sqrt{\pi f \mu \sigma}}$.
It is inversely proportional to the square root of frequency ($\delta \propto 1/\sqrt{f}$). If the frequency is decreased by 4 times, the skin depth increases by a factor of $\sqrt{4} = 2$. Hence, it is doubled.