When a capacitor is connected in series LR circuit, the alternating current flowing in the circuit

An alternating current is given by $\mathrm{I}=100 \sin (50 \pi \mathrm{t})$. How many times will the current become zero in one second?

A coil of self inductance L is connected in series with a bulb B and an a.c. source. Brightness of the bulb decreases when

In series LCR resonant circuit, the capacitance is changed from C to 3 C . To obtain the same resonant frequency, the inductance should be changed from $L$ to