Excerpt from Electrical Laboratory Notes and FormsAt every point. In the neighbourhood of a magnet or conductor carrying a current there is a magnetic force, and the region within which this force manifests itself is called a magnetic field. At each point in a magnetic field the magnetic force has a certain direction and magnitude. F a. Very long magnetic needle is held with one pole at any point in a magnetic field and the other pole removed quite away from that point, the magnetic force tends to urge the pole held in that field in a certain direction, with a force which is proportional to the product of the strength of the pole and the strength of the field at that point. If a very small magnetic needle, pivoted at the centre, is held at any point in a field, two equal and opposite forces act upon its ends. If l is the magnetic length of this needle, m the strength of each pole, and H the strength of the field, then, when the small needle is held so that its length or axis is at right angles to the direction of the field, the couple or torque acting on it is equal to.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.