A 2.74 F and a 7.46 F capacitor are connected in series across a 40.0-V battery. A 10.1 F capacitor is then connected in parallel across the 2.74-uF capacitor. Determine the voltage across the 10.1 F capacitor.

14.7 Volt

Explanation:

C1 = 2.74 F, C2 = 7.46 F, C3 = 10.1 F

Here C1 and C3 are in parallel

So, Cp = C1 + C3 = 2.74 + 10.1 = 12.84 F

Now Cp and C2 are in series

1 / C = 1 / Cp + 1 / C2

1 / C = 1 / 12.84 + 1 / 7.46

C = 4.72 F

Let q be the total charge

q = C V = 4.72 x 40 = 188.8 C

Voltage across C2

V2 = q / C2 = 188.8 / 7.46 = 25.3 V

Voltage across C2 or c3

V' = V - V2 = 40 - 25.3

V' = 14.69

V' = 14.7 Volt