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A series L-C-R circuit is connected to an alternating voltage source of frequecy f. If the current leads the e.m.f. By `45^(@)`, then the value of C isA. `1/(2 pi f(2 pi fL+R))`B. `1/(2 pi fC(2 pi fL-R))`C. `1/(pi f(2 pi fL-R))`D. `1/(pi f(2 pi fL+R))` |
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Answer» Correct Answer - B In a series L-C-R circuit, `tan phi = (X_(C)-X_(L))/R` As the current leads the e.m.f. `X_(C) gt X_(L)`. `:. tan 45^(@) = (X_(C)-X_(L))/R =1` `:. X_(C) = X_(L)+R` `:. 1/(omega C) = omega L + R :. Omega C = 1/(omegaL+R)` `:. C = 1/(omega(omegaL+R)) = 1/(2pi f(2 pi f L+R))`. |
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