Electro Magnetic Induction And Alternating Currents Question 414

Question: A resistance of 20 Ω is connected to a source of an alternating potential V= 220 sin(100πt) . The time taken by the current to change from the peak value to rms value, is

Options:

A) 0.2,s

B) 0.25,s

C) 0.25×103,s

D) 0.25×103,s

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Answer:

Correct Answer: D

Solution:

  • Both V and I are in the same phase.

    So, let us calculate the time taken by the voltage to change from peak value to rms value. Now 220 sin100πt1

    Or 100πt1=π2

    or t1=1200s Again, 2202=220sin100πt2

    Or 12=sin100πt2 or 100πt2=3π4

    Or t2=3400s

    Required time =t2t1=1400s=2.5×103s



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