In India,$AC$ voltage becomes zero how many times in $1$ $sec$?

An $AC$ source has a voltage of $220V$ and a frequency of $50\,Hz$. How much time (in $sec$) does it take for the voltage to reach zero from its maximum value?

Find the effective value of current $i = 2\sin(100\pi t) + 2\cos(100\pi t + 30^{\circ})$.

What is $AC$ voltage? Write the equation for $AC$ voltage.

If a direct current of $a$ ampere is superimposed with an alternating current $I = b \sin \omega t$,then the effective value of the resulting current is

The phase difference between the voltage and the current in an $AC$ circuit is $\pi / 4$. If the frequency is $50 \ Hz$,then this phase difference will be equivalent to a time of: