Alternating Current

JEE Main level, numerical answer, medium

63 of 190

Question 63 of 190

A capacitor of reactance 43Ω4 \sqrt{3} \Omega and a resistor of resistance 4Ω4 \Omega are connected in series with an ac source of peak value 82 V8 \sqrt{2} \mathrm{~V}. The power dissipation in the circuit is ________ W.

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Answer: 4


Z=R2+X2 LZ=42+(43)2=8ΩVrms=V2=822=(8 V)Irms=VrmsZ=88=1 A\begin{aligned} & \mathrm{Z}=\sqrt{\mathrm{R}^2+\mathrm{X}^2 \mathrm{~L}} \\ & \mathrm{Z}=\sqrt{4^2+(4 \sqrt{3})^2}=8 \Omega \\ & \mathrm{V}_{\mathrm{rms}}=\frac{\mathrm{V}}{\sqrt{2}}=\frac{8 \sqrt{2}}{\sqrt{2}}=(8 \mathrm{~V}) \\ & \mathrm{I}_{\mathrm{rms}}=\frac{\mathrm{V}_{\mathrm{rms}}}{\mathrm{Z}}=\frac{8}{8}=1 \mathrm{~A}\end{aligned}
Power dissipated
=Irms2×R=1×4=(4 W)=\mathrm{I}_{\mathrm{rms}}^2 \times \mathrm{R}=1 \times 4=(4 \mathrm{~W})

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