In the present chapter we are going to consider some common-sense aspects of doing experiments. They apply to all experiments, from the most elementary and simple to the most advanced and elaborate.

Preliminary experiment

In a real experiment, as opposed to an exercise, one nearly always does a trial experiment first. This serves several purposes.

(a) The experimenters ‘learns’ the experiment. Every experiment has its own techniques and routines, and the experimenter needs some training or practice in them. It is nearly always true that the first few measurements in an experiment are not as reliable or useful as the later ones, and it is usually more economical in time to have an initial period for finding out the best way of making the measurements and recording the results.

(b) The various pieces of apparatus are checked to see that they are working properly.

(c) A suitable range for each variable in the experiment is found.

(d) The errors in the different quantities can be estimated. As we have seen, this influences the strategy of the experiment proper, in the sense that more attention is given to those quantities whose errors give the major contributions to the final error.

Points (c) and (d) really add up to saying that any serious experiment must be planned, and that a few trial measurements provide a better basis for a plan than a lot of theory.