When electricity jumps between two conducting electrodes, such as two exposed pieces of wire, it makes an electrical arc. The air between the electrodes becomes ionised, allowing electrons to jump across and create a visual “bridge”. An electrical arc can produce high heat and a powerful light, making it useful in areas such as welding. Lightning is an example of a naturally occurring electric arc; the atmosphere is ionised and creates the visual spectacle.
Find out how a plastic bottle, water and a little bleach can make a cheap and long-lasting light bulb