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JEE Main 2021 (27 Aug, Shift 1) · AC Basics: Peak, RMS & Average Values

AC Basics: Peak, RMS & Average Values question from JEE Main 2021 (27 Aug, Shift 1)

Q37JEE Main 2021 · 27 AUG · SHIFT 1Difficult

AC Basics: Peak, RMS & Average Values

The alternating current is given by i={42sin⁡(2πTt)+10}Ai = \left\{\sqrt{42} \sin\left(\frac{2\pi}{T} t\right) + 10\right\} A

The r.m.s. value of of this current is ................. A.

Numerical answer type. Work it out, then open the answer.

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Answer: 11

  1. i2=42sin⁡2ωt+2042sin⁡ωt+100i^2 = 42\sin^2\omega t + 20\sqrt{42}\sin\omega t + 100
  2. Over a cycle ⟨sin⁡2ωt⟩=12\langle\sin^2\omega t\rangle = \frac{1}{2} and ⟨sin⁡ωt⟩=0\langle\sin\omega t\rangle = 0.
  3. irms2=21+0+100=121i_{rms}^2 = 21 + 0 + 100 = 121
  4. irms=11i_{rms} = 11 A
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