The object of practical physics

Abstract

This book is intended to help you to do practical physics at college or university: its aim is to make the laboratory work more useful and profitable. We may start by asking what is the object of laboratory work in a university physics course. There are several possible objects. Laboratory work may serve (a) to demonstrate theoretical ideas in physics, (b) to provide a familiarity with apparatus , (c) to provide a training in how to do experiments . Let us consider each of these in turn. Seeing something demonstrated in practice is often a great help in understanding it. For example, interference in light is not an intuitive concept. The idea that two beams of light can cancel each other and give darkness takes a little swallowing, and most people find it helpful to be given a visual demonstration. A demonstration is useful for another reason – it gives an idea of orders of magnitude. The interference fringes are in general close together, which indicates that the wavelength of light is small compared with everyday objects. But the demonstration is no substitute for a proper explanation, which goes into the details of geometry and phase relations. So the first object, the demonstration of theoretical ideas, has a definite but limited usefulness.