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Question
An inductor-coil, a capacitor and an AC source of rms voltage 24 V are connected in series. When the frequency of the source is varied, a maximum rms current of 6.0 A is observed. If this inductor coil is connected to a battery of emf 12 V and internal resistance 4.0 Ω, what will be the current?
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Solution
RMS value of voltage, Erms = 24 V
Internal resistance of battery, r = 4 Ω
RMS value of current, Irms = 6 A
Reactance (R) is given by,
`R = E/I_{rms}`
`rArr R = 24/6 =4 Ω`
Let R' be the total resistance of the circuit. Then,
R' = R + r
`rArr R = 4Ω + 4Ω `
`rArr R = 8 Ω `
Current, I = `12/8 A`
= 1.5 A
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