Comprehensive and up to date, this fourth edition should be a useful reference tool for students of physics, either at school or at university. Containing over 4000 clear and precise entries, and now with biographies of key scientists, it covers all the commonly encountered terms and concepts of physics. New entries include group theory, radioisotope imaging, fractional quantum Hall effect, and Lorentz force, and the work also contains feature articles on important topics and chronologies charting discoveries in main fields of the subject.