A) 0.56
B) 0.64
C) 0.80
D) 0.33
Correct Answer: C
Solution :
Power factor\[(cos\phi )\]is a ratio of resistance and impedance of AC circuit. Power factor of AC circuit is given by \[\cos \phi =\frac{R}{Z}\] (i) Where R is resistance employed and Z the imped- ance of the circuit. \[Z=\sqrt{{{R}^{2}}+({{X}_{L}}-X_{C}^{2})}\] (ii) Eqs. (i) and (ii) meet to give, \[\cos \phi =\frac{R}{\sqrt{{{R}^{2}}+{{({{X}_{L}}-{{X}_{C}})}^{2}}}}\] Given, \[R=8\Omega ,{{X}_{L}}=21\Omega ,{{X}_{C}}=25\Omega \] \[\cos \phi =\frac{8}{\sqrt{{{(8)}^{2}}+{{(31-25)}^{2}}}}=\frac{8}{\sqrt{64+36}}\] \[\cos \phi =0.80\]You need to login to perform this action.
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