6.1 Capacitors

Most modern day electronic devices such as mobile phones, cameras, laptops and defibrillators all contain capacitors. Medical equipment uses capacitors to measure blood flow and they are used to measure the amount of fuel left in an aeroplanes tank. Accelerometers and tilt sensors make use of capacitors so that airbags can be deployed effectively. Touch switches and fingerprint sensors also make use of the capacitance of the human body.

Despite the widespread use of devices that contain capacitors, it is still the case that electrical energy is difficult to store in large quantities for long periods of time.

This section introduces the basic properties of capacitors and how they are used in electrical circuits. The use of capacitors as a source of electrical energy is then developed.

This section introduces the mathematics of exponential decay, which is also required for the decay of radioactive nuclei in 6.4