# A-level Physics (Advancing Physics)/Capacitors/Worked Solutions

**1. A 2 mF capacitor is connected to a 10V DC power supply. How much charge can be stored by the capacitor?**

Note that this is the maximum charge - since capacitors charge, as well as discharge, exponentially, we would have to leave the capacitor charging for an infinitely long period of time to charge it to capacity.

**2. What is the highest possible energy stored by this capacitor?**

**3. The capacitor is placed in series with a 5Ω resistor and charged to capacity. How long would it take for the charge in the capacitor to be reduced to 1 mC?**

**4. After this time has elapsed, how much energy is stored in the capacitor?**

**5. What is the capacitance of the equivalent capacitor to the following network of capacitors?**

First, ignore the fact that the capacitances are in mF, not F - we will not be using any other units, so if we put in mF, we will get out mF.

Then work out the equivalent capacitance of the second row:

Then work out the equivalent capacitance of the third row:

The equivalent capacitance of the first row is easy, since it contains just 1 capacitor: 3mF. So, the total equivalent capacitance is: