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Photovoltaic Cannon

Teams will devise a device to launch a ping-pong ball as far as possible using light as the input energy source.


Teams will design a device to launch a ping-pong ball as far as possible using light as the input energy source. Prior to launch, a team will set up the device inside a 20 cm x 20 cm x 20 cm transparent enclosure on a table three feet above the floor. One side of the enclosure will be equipped with an automatic door. The device will be loaded into the enclosure through this door. After the device has been set up and the projectile loaded, contest judges will check that no energy is stored anywhere in the device. Then, the light source will be switched on, the device will be exposed to uniform light for thirty seconds, after which the automatic door will close. If no launch is achieved, the launch distance will be recorded as zero. The launch distance will be measured from the opening in the enclosure, to the spot of first impact of the ping-pong ball. Each team will be given three launch attempts. The best distance of the three will be recorded, and the team achieving the greatest launch distance will be the winner.


  1. Devices may use no energy other than the light provided (no pre-charged batteries or capacitors, explosives, stretched springs, etc.)

  2. The launch mechanism must be electrical or electromechanical.

  3. Each device must fit entirely within the 20 cm x 20 cm x 20 cm enclosure.

  4. Student teams will not be allowed to have any interaction with their devices after the judges have inspected them. This includes physical contact, radio links, and all other forms of interaction. The device must operate completely automatically.

  5. Student teams will be required to demonstrate to the judges the principles of operation of their devices. They will also be required to demonstrate that, prior to the light exposure, there is no stored energy anywhere in the device. Devices must include a means for dissipating any energy in any energy storage units contained in the device.