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Concepts Of Physics MCQ Edition [Volume 2]PhysicsAlternating Current

An alternating current is expressed as i = i₁ t + i₂ t . The rms value of this current is

Options

  1. A|i₁ - i₂| 2
  2. Bi₁^2 + i₂^2 2
  3. Ci₁^2 + i₂^2
  4. Di₁ + i₂ 2

Correct answer

B. i₁^2 + i₂^2 2

Step-by-step solution

The given alternating current is i = i₁ t + i₂ t . The rms value of the current is given by i_ rms = i^2 , where i^2 is the mean square value of the current over a complete cycle. Squaring the current expression: i^2 = (i₁ t + i₂ t)^2 i^2 = i₁^2 ^2 t + i₂^2 ^2 t + 2 i₁ i₂ t t Taking the average over one complete cycle: i^2 = i₁^2 ^2 t + i₂^2 ^2 t + i₁ i₂ 2 t Since the average values over a full cycle are ^2 t = 1 2 , ^2 t = 1 2 , and 2 t = 0 , we get: i^2 = i₁^2 ( 1 2 ) + i₂^2 ( 1 2 ) + 0 = i₁^2 + i₂^2 2 Therefore,

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