Electro Magnetic Induction And Alternating Currents Question 197

Question: An ac source of angular frequency co is fed across a resistor R and a capacitor C in series. The current registered is I. If now the frequency of source is changed to ω/3 (but maintaining the same voltage), the current in the circuit is found to be halved. Then the ratio of reactance to resistance at the original frequency ω is

Options:

A) 3/5

B) 5/3

C) 2/3

D) 3/2

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Answer:

Correct Answer: A

Solution:

  • According to given problem,

    I,=VZ,=V[R2+(1/Cω)2]1/2 …(i) and

    I2,=V[R2+(3/Cω)2]1/2 …(ii) Substituting the value of I from eq. (i) in (11),

    4,(R2+1C2ω2)=R2+9C2,ω2 i.e.,

    1C2,ω2,=35,R2 so that XR



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