EMP
As an end of course assignment in my AP Physics C class, I decided to build an electromagnetic pulse (EMP) device. By creating an electromagnetic field (running high voltage through a coil of wire), pulses of waves are produced. Bringing some kind of circuitry (electronic device) close to these waves can induce a current in the circuit, shorting causing the device to malfunction or fry.
The EMP circuit consists of a battery's output voltage being stepped up to 400k volts. With a high voltage hooked up to a copper coil, electromagnetic waves are generated. A spark gap is used to modulate this wave into pulses, generating the EMP effect.