$AC$ measuring instruments measure

What is the $r.m.s.$ value of an alternating current which,when passed through a resistor,produces heat that is thrice the heat produced by a direct current of $2 \ A$ in the same resistor (in $A$)?

An alternating voltage is given by: $e = e_1 \sin \omega t + e_2 \cos \omega t$. Then the root mean square $(RMS)$ value of the voltage is given by:

The average value of alternating current over a complete cycle is

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?

An alternating current is given by $i = i_1 \sin \omega t + i_2 \cos \omega t$. The rms current is given by