What is the power factor in an R-L circuit with a 60 degree phase angle between voltage and current?

In an R-L (resistive-inductive) circuit, the power factor is calculated using the cosine of the phase angle between the voltage and current. The power factor is an important concept as it represents the fraction of the total power that is used effectively in performing work, which is especially relevant in AC circuits.

For a phase angle of 60 degrees, you take the cosine of 60 degrees to determine the power factor:

[ \text{Power Factor} = \cos(60^\circ) ]

The cosine of 60 degrees is equal to 0.5. This means that in an R-L circuit with a phase angle of 60 degrees, 50% of the power is effectively utilized, while the rest may be reactive power that does not perform useful work.

This understanding directly aligns with the correct answer in the context of the options provided.