Electro Magnetic Induction And Alternating Currents Question 158

Question: In a series LCR circuit, the difference of the frequencies at which current amplitude falls to 12 of the current amplitude at resonance is

Options:

A) R2πL

B) RπL

C) 2RπL

D) 3R2πL

Show Answer

Answer:

Correct Answer: A

Solution:

  • At resonance

IR=E0RIR2=E02R=E0R2+(ωL1ωC)2
ω1L1ω1C=R

and ω2L1ω2C=+R
,L(ω1+ω2)=(ω1+ω2ω1ω2)1Cω1ω2=1LC

and L(ω2ω1)+(ω2ω1ω1ω2)1C=2R

Putting value of ω1 and ω2

we get ω2ω1=RLf2f1=R2πL



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