Marks 1
A single-phase triac based AC voltage controller feeds a series RL load. The input AC supply is 230 V, 50 Hz. The values of R and L are 10 Ω and 18.37 mH, respectively. The minimum triggering angle of the triac to obtain controllable output voltage is
Marks 2
An ideal sinusoidal voltage source $v(t)=230 \sqrt{2} \sin (2 \pi \times 50 t) \vee$ feeds an ideal inductor $L$ through an ideal SCR with firing angle $\alpha=0^{\circ}$. If $L=100 \mathrm{mH}$, then the peak of the inductor current, in ampere, is closest to
In the following circuit, the average voltage
$$ V_0=400\left(1+\frac{\cos \alpha}{3}\right) V $$
where $\alpha$ is the firing angle. If the power dissipated in the resistor is 64 W , then the closest value of $\alpha$ in degrees is
