The Peltier effect is a thermoelectric phenomenon that occurs when an electric current passes through two different materials, creating a heat flux at their junction. This effect was discovered by French physicist Jean Charles Athanase Peltier in 1834. When a voltage is applied across a Peltier cooler, a difference in temperature will build up between the two sides, resulting in cooling on one side and heating on the other. The Peltier effect can also be used as a thermoelectric generator, where one side of the device is heated to a temperature greater than the other side, resulting in a difference in voltage between the two sides (the Seebeck effect). The amount of heat that can be moved is proportional to the current and time, and Peltier elements are commonly used in consumer products such as camping coolers, cooling electronic components, and small instruments. They are also used in scientific devices, such as thermal cyclers used for DNA amplification.