Question

Question:An ac resistance is higher than a dc resistance.

(a) True

(b) False

Short answer

Answer

Therefore, the correct option is (a) True.

Step-by-step solution

Explain ac resistance

The ac resistance is related with the loss resistance and is given by the formula ${\mathbf{\text{R}}}_{\mathbf{\text{ac}}}\mathbf{=}\frac{{\mathbf{\text{P}}}_{\mathbf{\text{loss}}}}{\left|I^2\right|}$, is the sqmil.

With the increase in frequency, the conduction losses due to skin effect increases due to which the power loss also increases.

Whereas this process called skin effect lead to smaller current density at the inner conductor.

This phenomenon causes the ac resistance to increase at higher frequencies.

Explain dc resistance 

The DC resistance can be easily calculated by emf generated between the conductors (inner and outer) of a line, divided by current flowing through them.

Also, it is independent of the dimensions of the conductor and frequency of operation.

Generally,at power frequencies (60 Hz), the ac resistance is at most a few percent higher than the dc resistance.

Thus option (a) is correct.