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JEE Main202118 Mar 2021Morning ShiftPhysicsAlternating CurrentActual

An A C 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 :

Options

  1. A2 . 5   ms
  2. B25   ms
  3. C2 . 5   s
  4. D0 . 25   ms

Correct answer

A. 2 . 5   ms

Step-by-step solution

i = i 0 cos ( ω t ) i = i 0 at t = 0 i = i 0 2 at ω t = π 4 t = π 4 ω = π 4 ( 2 π f ) = 1 8 f t = 1 400 = 2 . 5   ms

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