An electric motor is often described as “a device that converts electrical energy…
PHYSICS · Multi-part · CBSE · Physics · Magnetic Effects of Electric Current · Magnetic Effects of Electric Current
Problem
An electric motor is often described as “a device that converts electrical energy into mechanical energy by the action of a magnetic field on a current-carrying coil.” Consider the key components that make this conversion possible.
(a) State the principal role of the permanent magnet (or field electromagnet) in the motor.
(b) Explain why the short sides of the rectangular coil experience negligible force compared with the long sides in typical motor design.
(c) Describe in detail the necessity of using a split-ring commutator rather than connecting the coil directly to the battery leads.
(d) If, in a given motor, the brushes were positioned so that they make contact exactly when the plane of the coil is parallel to the magnetic field instead of perpendicular, explain qualitatively how the performance of the motor would change.