    Question

# A coil has an inductance of 0.7 H and is connected in series with a resistor of resistance 220 Ω. When an alternating emf of 220 V at 50 cycles/s is applied to it, the wattless component of the current in the circuit is equal to

A
5 A
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B
0.5 A
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C
0.7 A
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D
7 A
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Solution

## The correct option is B 0.5 AGiven:- L=0.7 H ; R=220 Ω ; V=220 V f=50 Hz Now, Inductive reactance XL=ωL=2πfL XL=2π×50×0.7 ⇒XL=219.9 Ω≈220 Ω Drawing the impedance triangle Z=√2202+2202=220√2 Ω As we know that, tanϕ=XLR=ωLR=220220=1 ⇒ϕ=45∘ Now, current in the circuit I=VZ=220220√2=1√2 A Wattless component of current =Isinϕ =1√2×1√2=0.5 A Hence, option (B) is correct. Concept:- Wattless current is the current in the circuit in which average power consumed by the circuit is zero.  Suggest Corrections  0      Similar questions
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