Question

When the resistance is greater than the capacitive reactance in a series RC circuit, what is the value of the phase angle?

Answer 1

The resistance (`R`), reactance (`X_C`), and overall impedance (`Z`) are related by:

`Z = sqrt(R^2 + X_C^2)`

Thus, there is a right triangle such that `Z` is the hypotenuse, and `R` and `X_C` are two legs. Using the angle between `Z` and `R`, we have:

`tanphi = (X_C)/R`

thus the phase shift `phi` is:

`phi = arctan((X_C)/R)`

Let's say that `R > X_C`. That means the argument of `arctan` is less than `1`, so `-pi/4 < phi < pi/4`.