Solution

$$E_{rms}=220V$$
Frequency = 50 Hz
(a) $$E_{rms}=220V$$=$$\displaystyle\frac{E_{0}}{\sqrt{2}}$$
$$\Rightarrow E_{0}=E_{rms}\sqrt{2}=\sqrt{2}\times 220=1.414\times 220=311.08V=311V$$
(b) Time taken for the current to reach the peak value = Time taken to reach the 0 value from r.m.s.
$$\displaystyle I=\frac{I_{0}}{\sqrt{2}}\Rightarrow \frac{I_{0}}{\sqrt{2}}=I_{0}\sin wt$$
$$\displaystyle\Rightarrow wt=\frac{\pi }{4}$$
$$\displaystyle\Rightarrow t=\frac{\pi }{4}=\frac{\pi }{2\pi f}=\frac{\pi }{8\pi 50}=\frac{1}{400}=2.5ms$$