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In series `LR` circuit, `X_(L) = 3 R`. Now a capacitor with `X_(C ) = R` is added in series. The ratio of new to old power factorA. `sqrt2`B. `(1)/(sqrt2)`C. 2D. 1 |
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Answer» Correct Answer - A In series `LR` circuit, Power factor, `cos phi_(1) = (R )/(Z)` `= (R )/(sqrt(R^(2) +X_(L)^(2))) = (R )/(sqrt(R^(2) + 9 R^(2))` ` = (R )/(R sqrt(10)) = (1)/(sqrt10)` When capacitor with `X_(C ) = R` is added in series, new power factor, `phi_(2) = (R )/(Z) = (R )/(sqrt(R^(2) + (X_(L) - X_(C ))^(2)))` `cos phi_(2) = (R )/(sqrt(R^(2) + (3 R - R)^(2))) = (R )/(R sqrt5)` `:. (cos phi_(2))/(cos phi_(1)) = (1)/(sqrt5) sqrt(10)/(1) = sqrt2` |
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