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Question: Answered & Verified by Expert
A 10 Ω resistance is connected across 220 V-50 Hz AC supply. The time taken by the current to change from its maximum value to the rms value is:
PhysicsAlternating CurrentJEE MainJEE Main 2021 (25 Jul Shift 2)
Options:
  • A 2.5 ms
  • B 1.5 ms
  • C 3.0 ms
  • D 4.5 ms
Solution:
2342 Upvotes Verified Answer
The correct answer is: 2.5 ms

i=i0sinωt

When i=i0

i0=i0sinωt1ωt1=π2 (1)

When i=i02

i02=i0sinωt2ωt2=π4 (2)

Time taken by current from maximum value to rms value, t1-t2=π2ω-π4ω=π4ω=π4×2πf

=18×50

=1400sec

=2.5 ms

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