Page 519 - Basic Electrical Engineering

The field produced is at right angles to the length of the current-carrying
conductor.

Example 5.12 A rectangular coil ABCD of size 20 cm × 10 cm is placed 1
cm away from a long current-carrying conductor with its longer sides parallel
to the conductor. A current of 100 A is flowing through the long conductor

while the coil is carrying a current of 10 A. Calculate the resultant force
developed on the coil.

Solution:

Force will be developed between the longer sides of the coil and the
conductor as they are parallel to each other. There will be force of attraction

with one coil side and force of repulsion with the other. The difference
between the two forces will be the resultant force acting on the coil. There

will be no force developed on the sides which are perpendicular to the
conductor as shown in Fig. 5.32.

Force experienced per unit length by a current-carrying conductor due to
flux density created by the other current-carrying conductor is

Force of attraction between the conductor and side AB

Force of repulsion between the conductor and side CD