Topic: Electromagnetics
Which of the following has the highest skin depth?
- A. Al
- B. Ag
- C. Au
- D. Cu
Answer: A. Al
Explanation: Skin depth $\delta = \sqrt{\frac{2}{\omega \mu \sigma}}$. Skin depth is inversely proportional to the square root of conductivity ($\sigma$). Since Aluminum (Al) has the lowest conductivity among the given options (Ag, Cu, Au, Al), it will have the highest skin depth.