An alternating current of frequency `'f'` is flowing in a circuit containing a resistance `R` and a choke `L` in series. The impedence of this circuit is

Options

A. `R+2 pi f pi L`
B. `sqrt(R^2+L^2)`
C. `sqrt(R^2 2 pifL)`
D. `sqrt(R^2+4pi^2f^2L^2)`

Answer

D