Question 5.8: What is skin effect?...

Every conductor line has resistance and inductance! When you pass AC in a conductor (imagine a rod), then due to its alternating nature and with the conductor inductance, it finds some opposition to the flow of current in the regions closer to the center of the conductor. Since this inductive reactance is stronger at the center, the current tends to avoid that area and prefers flowing on the periphery or the skin of the conductor. Hence, skin effect. The more the frequency, the stronger is the reactance. The concept of skin effect is shown in Figure 5.6.