InterviewSolution
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InterviewSolution
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A coil of inductive reactance `31 Omega` has a resistance of `8 omega`. It is placed in series with a condenser of capacitive reactance `25 Omega`. The combination is connected to an `ac` source of `110 V`. The power factor of the circuit isA. `0.56`B. `0.64`C. `0.80`D. `0.33` |
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Answer» Correct Answer - C Power factor `(cos phi)` is a ratio fo resistance and impedence of `AC` circuit. Power factor of `AC` circuit is given by `cos phi=R/Z......(i)` Where `R` is resistance employed and `Z` the impedence of the circuit. `Z=sqrt(R^(2)+(X_(L)-X_(C)^(2)))........(ii)` Eqs (i) and (ii) meet to give, `cos phi=R/(sqrt(R^(2)+(X_(L)-X_(C))^(2)))........(iii)` Given, `R=8 Omega, X_(L)=21Omega, X_(C)=25 Omega` `cos phi=8/(sqrt((8)^(2)+(31-25)^(2)))=8/(sqrt(64+36))` `cos phi=0.80` |
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