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

Answer

B

Explanation

`Z=sqrt(R^(2)+X_(L)^(2)), X_(L)=omega L` and `omega=2pif`
`:. Z=sqrt(R^(2)+4pi^(2)f^(2)L^(2))`