The Peltier element contains many PN transitions. When it is powered by electricity, one side is heated and the other cooled. Which plate will heat up and which one will cool depends on which of the ends is plus or minus. In order not to overheat that part that is heated it is necessary to cool down. The temperature of the cold side depends on how cool the heated side is. It is possible to achieve a temperature of -15 ℃ on the cold side when cooling the hot side to +6 ℃. It is used in refrigeration bags, water dispensers (water cooling machines) and cooling electronic devices. The element of Peltier also has the opposite effect. It can also be used as a voltage generator, then called the Zeebeck element. This is achieved by cooling one side and at the same time heating the other. At the output of the element, a potential difference (electrical potential) is created. The magnitude of the voltage obtained depends on a number of factors, such as what is the difference in temperature, how much the element is wool, etc.