Question

Consider the situation of the previous problem. If 1⋅0 µC is placed on the upper plate instead of the middle, what will be the potential difference between (a) the upper and the middle plates and (b) the middle and the lower plates?

Answer 1

When 1µC charge is given to the upper plate, the charge gets distributed. The two sides of the upper plate have +0.5 µC charge. One side of the middle plate facing the upper plate has $-$0.5 µC charge and the other side has +0.5 µC charge. Similarly, one side of the lower plate facing the middle plate has $-$0.5 µC charge and the other side has +0.5 µC charge.


(a) Effective charge on the capacitor formed by the upper and middle plates = 0.5 µC
Capacitance = 50 nF = 0.05 µF
∴ Potential difference between the plates, $V=\frac{Q}{C}=\frac{0.5\mathrm{\mu C}}{0.05\mathrm{\mu F}}=10\mathrm{V}$

(b) Effective charge on the capacitor formed by the middle and lower plates = 0.5 µC
Capacitance = 0.50 µF
∴ Potential difference between the plates, $V=\frac{Q}{C}=\frac{0.5\mathrm{\mu C}}{0.05\mathrm{\mu F}}=10\mathrm{V}$