Born at Ardrossan in Scotland, Kerr studied at Glasgow University and carried out research work under Lord Kelvin. He taught mathematics at a training college in Glasgow. He is remembered for his work on polarized light, in which he discovered that certain substances placed in a strong electric field exhibit birefringence (the Kerr effect). Kerr also described the behavior of polarized light when reflected from the polished pole of an electromagnet (the Faraday effect).