A series circuit with L = 0.12H, C = 0.48 mF and R = 25 ohm, is connected to a 220V variable frequency power supply. At what frequency is the circuit current maximum ?

Explanation

`L = 0.12 H`
`C = 0.48 mF = 0.48 xx 10^(-3) F`
` R = 25 Omega`
`E_v = 220 V`
Current flowing in the circuit is maximum when
`X_L = X_C`
`implies 2pi vL = 1/(2pivC)`
`v^2 =1/(4pi^2LC)`
`v = 1/(2pisqrt(LC))`
`v=1/(2xx3.14 sqrt(0.12xx0.48 xx10^(-3)))`
`=1/(6.28 sqrt(0.057xx10^(-3)))`
`1/(6.28 sqrt(0.057xx10^(-4)))`
`1/(6.28xx0.755xx10^(-2))`
`v=100/(6.28xx0.755)=21.1Hz`