A sinusoidal alternating voltage has a root-mean-square (r.m.s.) potential difference (p.d.) of 
and a frequency of 
.
The alternating voltage is applied across a resistor of resistance 
. By considering the peak voltage, show that the maximum power dissipated by the resistor is 
.
On the graph below, draw a smooth curve to show how the power 
dissipated in the resistor varies with time 
between 
and 
. Assume that 
when .
Use your line in (b) to explain why the mean power dissipated in the resistor is 
.
