J J Thomson with his son, George, c 1909.
© Science Museum / Science & Society Picture Library
One of a set five family photographs in a frame. English physicist Sir Joseph John Thomson (1856-1940) studied sciences at Trinity College, Cambridge. After graduating, he continued to work at Cambridge University and in 1896 began experiments on cathode rays. He showed that cathode rays were particles much smaller than the atom with a negative charge. These particles were later renamed electrons. In 1906 he was awarded the Nobel Prize for Physics for his research on conduction through gases. In 1912 he went on to develop mas spectrometry (the study of the structure and properties of molecules and compunds). Photographed with his son, the noted physicist George Paget Thomson (1892-1975).