Question

The domestic power supply of 220 V,50 Hz is connected to a resistor.What is the time taken by the ac current flowing through the resistor to change from its peak value to its r.m.s value?

• A. 0.005 s
• B. 0.0025 s
• C. 0.002 s
• D. 0.004 s

Answer 1

The correct option is A 0.005 s

$i_{rms}=\frac{v_0}{\sqrt{2}}$

And for a resistive load current $4$ voltage are in phase

$\therefore$`Time takes for curves to change to is rms value is same in which voltage changes its peak value to rms value

$v=v_0\sin wt$

$=\frac{v_0}{\sqrt{2}}=v_0\sin wt$

$\sin wt=\frac{1}{\sqrt{2}}$

$=wt=\frac{\pi }{2}$

$=2\pi \times 50xt=\frac{\pi }{2}$

$=t=\frac{1}{50\times 4}=\frac{1}{200}=0.005$

Hence$,$ option $\left(A\right)$ is correct$.$