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Question
Three capacitors of capacities 8 μF, 8 μF and 4 μF are connected in a series and potential difference of 120 volt is maintained across the combination. Calculate the charge on capacitor of capacity 4 μF.
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Solution
Given: C1 = 8 μF, C2 = 8 μF, C3 = 4 μF, V = 120 volt
To find: Charge on the capacitor C3
`1/C_s=1/C_1+1/C_2+1/C_3`
`C=Q/V`
`1/C_s=1/C_1+1/C_2+1/C_3`
`=1/8+1/8+1/4`
`C_s=2muF=2xx10^-6F
In series combination,
Q1 = Q2 = Q3
Using formula (ii),
`Q = C_sV`
`Q=2xx10^-6xx120=240xx10^-6C`
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