3. (Total \( 10\% \) ) For the RL circuit in Fig. 3, assume \( Vs = V_{m}cos\omega t \)

(a) Obtain the transfer function \( V{0} / V{s} \) (5%).
(b) Sketch its frequency response for the magnitude in dB scale. Mark the magnitude and the frequency of the half power point. (5%)

Fig. 3

Fig. 4