Referring to the Fig. Q.4, a resistive load of 15 is connected to a voltage source

Referring to the Fig. Q.4, a resistive load of 15 Ω is connected to a voltage source of 120V at 50 Hz through a back-to-back thyristor pair. The firing angles of thyristors T1and T2 are equal and at  α =3π . Determine 

(i)    the rms output voltage Vo; 

(ii)   the input power factor; 

(iii)  the average current through each thyristor; 

(iv)  the rms current through each thyristor. 

(v)   the rating of the thyristors.