JEE PYQ: Alternating Current Question 7
Question 7 - 2021 (18 Mar Shift 1)
An AC source rated 220 V, 50 Hz is connected to a resistor. The time taken by the current to change from its maximum to the rms value is:
(a) 2.5 ms (b) 25 ms (c) 2.5 s (d) 0.25 ms
Show Answer
Answer: (a)
Solution
$i = i_0 \cos(\omega t)$. At $t = 0$, $i = i_0$. At $i = \frac{i_0}{\sqrt{2}}$, $\omega t = \frac{\pi}{4}$. $t = \frac{\pi}{4\omega} = \frac{1}{8f} = \frac{1}{400} = 2.5$ ms.
BETA
