QJEEM21Pha85a: JEE Main 2021 Physics - Class 12 JEEM21Pha85a Solution: An AC source rated 220 V, 50 Hz is connected to a resistor. The …

Question

Verified Solution • 2025–26 Session moderate

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 :

Accepted Answer

I = I_{0} \sin ω t

\Rightarrow

\frac{I_{M}}{\sqrt{2}} = I_{M} \sin ω t

\Rightarrow

ω t = \frac{π}{4}

\Rightarrow

t = \frac{π}{4 ω}

= \frac{π}{4 (2 π f)}

\Rightarrow

t =

\frac{1}{8 \times 30} = \frac{1}{400}

= 2.5 ms

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