Calculating Charge on Each Plate of a Capacitor

Question:

It takes 18 J of energy to move a 0.30 mC charge from one plate of a 15 mF capacitor to the other. How much charge is on each plate?

Answer:

The amount of charge on each plate is equal to 0.9 Coulombs.

Calculation Method:

To calculate the amount of charge on each plate:

The formula for work done is: Work = qV

Given data:
Work done (W) = 18 J
Charge (q) = 0.30 mC
Capacitance (C) = 15 mF

We know that work done is equal to the product of charge and potential difference:

W = qV

But, we also know that potential difference (V) across a capacitor is given by V = Q/C, where Q is the total charge on the capacitor plates.

Substitute V = Q/C in the formula for work:

W = q(Q/C)

Making q the subject of the formula:

q = W(C)/Q

Substitute the given values in the formula:

q = (18 * 15 * 10^-6) / (0.3 * 10^-3)

Charge(q) = 0.9 Coulombs.