If skin depth of a conductor with frequency f Hz is d, what will be the new skin depth if the frequency increased to 4f : 

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  1. d/4 
  2. 2d 
  3. d/2
  4. 4d

Answer (Detailed Solution Below)

Option 3 : d/2
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Concept:

Skin depth (δ) is the distance into a conductor at which the current density falls to 1/e of its value at the surface due to the skin effect in AC systems.

The formula gives it: \( \delta = \sqrt{\frac{2}{\omega \mu \sigma}} \)

Where,

  • ω = 2πf (angular frequency)
  • μ = permeability of the material
  • σ = conductivity of the material

Explanation:

Since \( \delta \propto \frac{1}{\sqrt{f}} \)Skin depth is inversely proportional to the square root of the frequency.

If the frequency increases from f to 4f, then:

\( \delta_{\text{new}} = \frac{\delta}{\sqrt{4}} = \frac{\delta}{2} \)

Correct Option:

The new skin depth is: d/2

Correct Answer: 3) d/2

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