Question

Fleming's left-hand rule is used to find the direction of _________ acting on the current carrying conductor placed in a/an ________field.
(A) Force, Magnetic
(B) Force, Electric
(C) Torque, Magnetic
(D) Torque, Electric

Answer 1

Hint : From the statement of Fleming’s left- hand rule deduce the answer. Fleming’s left-hand rule states that, if the thumb, fore finger and middle finger are spread perpendicular to each other. Then if the Thumb represents the direction of force then The Fore finger represents the direction of the magnetic Field and the middle finger will represent the direction of the Current.

Complete Step By Step Answer:
We know that, when current flows through a conducting wire, and an external magnetic field is applied across that flow, the conducting wire experiences a force perpendicular to both to that field and to the direction of the current flow.

A left hand can be held, so as to represent three mutually orthogonal axes on the thumb, forefinger and middle finger .Each finger is then assigned to a quantity i.e. mechanical force, magnetic field and electric current. Then if the Thumb represents the direction of the force then the fore finger represents the direction of the magnetic Field and the middle finger will represent the direction of the Current.
Hence, Fleming’s left-hand rule is used to find the direction of force acting on the current carrying conductor placed in a magnetic field.
Hence, option ( A ) is correct.

Note :
Fleming’s left hand rule is a mnemonic to remember the direction of the force, current and the field. It is also called Fleming’s motor rule.
Left hand rule is used when motion of the current is due to the magnetic field but Fleming’s right hand rule or generator rule is used when there is a current due to a change in or motion of the magnetic field.