Alternating voltage:

$A$ $110 \, V$ $d.c.$ heater is used on an $a.c.$ source,such that the heat produced is the same as it produces when connected to $110 \, V$ $d.c.$ in the same time intervals. What would be the $r.m.s.$ value of the alternating voltage?

An alternating e.m.f. is given by $e = e_0 \sin \omega t$. In how much time will the e.m.f. have half its maximum value,if $e$ starts from zero? $(T = \text{time period}, \sin 30^{\circ} = 1/2)$

In an $A.C.$ circuit,$I_{\text{rms}}$ and $I_{0}$ are related as:

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

The voltage of domestic $AC$ is $220\,V$. What does this represent?