^Phase difference between I & V

When ac flows through a

(a) pure R, E & I are in phase i.e. Φ = 0⁰

(b) pure L, I  lags E by 90⁰ i.e. Φ = + 90⁰

(d) C, I leads E by 90⁰ i.e Φ = – 90⁰

The value of f for other cases depends upon the nature of circuit elements and their combinations.