Question

State Fleming’s right hand rule. For what purpose it is used?

Answer 1

Hint: According to Fleming’s right hand rule, we use thumb, index finger or the forefinger and the middle finger to represent directions of various parameters. It gives a relation between induced current, force and magnetic field in which the conductor is placed. This rule is used to determine the direction of the induced current in a conductor which is moving inside the magnetic field.

Complete solution:

Fleming’s right hand rule is an interpretation which gives the direction of induced current in a conductor when the conductor is moved in a magnetic field.

According to Fleming’s right hand rule, if we hold our right-hand thumb, forefinger or index finger and the middle finger all perpendicular to each other then the thumb represents the direction of the motion of the conductor or the direction of the applied force, the forefinger represents the direction of the magnetic field in which the conductor is placed and the middle finger represents the direction of induced current in the conductor.

Consider an experiment in which we use a stationary magnet and a coil which is connected to the galvanometer is moved through a magnetic field. When the coil is moved through the magnetic field, the galvanometer will show deflection in one direction due to the induced current. When the coil is again moved through the magnetic field, the galvanometer shows deflection in the opposite direction. This means that the direction of the induced current changes. This direction of the induced current can be determined using Fleming’s right hand rule.

Note:
Students should not get confused between the right-hand thumb rule and Fleming’s right hand rule. According to right hand thumb rule, the thumb indicates the direction of current and the direction in which the fingers wrap gives the direction of magnetic field. Students must remember that the Fleming’s right hand rule does not determine the magnitude but only the direction of magnetic field, current and force.