Maxwell, James Clerk

Scottish physicist. His main achievement was in the understanding of electromagnetic waves: Maxwell's equations bring together electricity, magnetism, and light in one set of relations. He studied gases, optics, and the sensation of colour, and his theoretical work in magnetism prepared the way for wireless telegraphy and telephony.

In developing the kinetic theory of gases, Maxwell gave the final proof that heat resides in the motion of molecules.

Studying colour vision, Maxwell explained how all colours could be built up from mixtures of the primary colours red, green, and blue. Maxwell confirmed English physicist Thomas Young's theory that the eye has three kinds of receptors sensitive to the primary colours, and showed that colour blindness is due to defects in the receptors. In 1861 he produced the first colour photograph to use a three-colour process.