1.

In a circuit L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by 45^(@). The value of C is

Answer»

`(1)/(PI f(2pi f L-R))`
`(1)/(2pi (2pi fL-R))`
`(1)/(pi f(2pi fL + R))`
`(1)/(2pi (2pi f L + R))`

Solution :`tan phi = (X_(C )-X_(L))/(R )rArr tan((pi)/(4))=((1)/(omega C)-omega L)/(R )`
Now,`R = (1)/(omega C)- omega L`
`rArr (R +2pi f L)=(1)/(2pi FC)`or`C=(1)/(2pi f(R +2pi f L))`


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