We all know that electricity travels from one place to another through metallic wires. Light can also travel through wires but these wires are not made of metals. They are made of glass or plastic. Light carrying wires are extremely thin and are called optical fibres. The narrow fibres have a thin core of glass of high refractive index surrounded by a thin cladding of another glass of lower refractive index. The core carries light and the covering helps bemd the light back to the core.
Fibres so prepared have to be aligned properly in the form of a bundle. They should not cross each other, otherwise the image transported by it will be scrambled. They are kept in straight lines. Once the aligned bundle is made it can be bent or turned in any desired direction. Fibre optic devices can transmit television programmes and telephone conversations. Many developed countries have installed telephone exchanges using fibre optic cables. The use of optical fibres in video text videophones and computer networks is increasing day by day.