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Alternating Current question

2016 · Q128
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Alternating Current question

2016 · Q128

NEETPhysicsAlternating CurrentMCQ+4 / −1
The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is
  1. A
    0.4
  2. B
    0.5
  3. C
    0.8
  4. D
    1.0
View written solutionFree

Correct answer: C

Power factor, cos ϕ\phi ϕ = RZ{R \over Z}ZR​

= VRV{{{V_R}} \over V}VVR​​

= VRVR2+(VL−VC)2{{{V_R}} \over {\sqrt {V_R^2 + {{\left( {{V_L} - {V_C}} \right)}^2}} }}VR2​+(VL​−VC​)2​VR​​

= 80802+(100−40)2{{80} \over {\sqrt {{{80}^2} + {{\left( {100 - 40} \right)}^2}} }}802+(100−40)2​80​

= 0.8

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