A metals atom contains outer electrons which move freely through the metallic material. These delocalised electrons are bound to the metal because of the attractive force of the atoms nuclei. However, when heated the electrons gain sufficient energy to escape from the...
The electron gun The electron gun produces a fine beam of electrons. It consists of a glass tube at a very low pressure. Electrons are produced by thermionic emission from a tungsten filament heated by a 6 V supply. A high positive potential is connected to a...
Resistor The resistor is used to measure the control the amount of current that flows through a circuit. The value and tolerance of the resistor is given by the four coloured bands on the resistor. The colours of the first three bands indicate the first digit, the...