Question

Explain Fleming’s left-hand rule with the help of a labelled diagram.

Answer 1

Hint: Fleming’s left-hand rule and Fleming’s right-hand rule were invented in the late 19th century by John Ambrose Fleming as an easy way to figure out movement direction in an electric motor, or electric current direction in an electric generator.

Complete Step-by-Step solution:


If a conductor connected to a circuit travels through a magnetic field, Fleming's right-hand rule (for generators) indicates the direction of induced current. It can be used to evaluate the current path within windings of a generator.
If current flows through a conducting wire and an external magnetic field is applied to that flow, the conducting wire feels a force perpendicular to both that field and the current flow direction (i.e., they are mutually perpendicular to each other). The left hand can be placed on the thumb, forefinger and middle finger to represent three mutually orthogonal axes. A quantity (mechanical power, magnetic field and electric current) is then allocated to each finger. The right and the left hand are respectively used for generators and motors.
The left-hand rule of Fleming is used for electric motors, while the right-hand rule of Fleming is used for electric generators. Regardless of the variations between cause and effect, separate hands must be used for motors and generators.

Note: Within an electric motor, there is the electrical current and the magnetic field (which are the causes), and they contribute to the force that produces the motion (which is the effect), so that the left-hand rule is applied. For an electrical generator, there is the motion and magnetic field (causes), and they contribute to the electrical current (effect) being generated and therefore the right-hand rule is used.