Force on a Current Carrying Conductor & Fleming's Left & Right Hand Rule | Science Class 10 PDF Download

FORCE ON A CURRENT CARRYING CONDUCTOR PLACED IN A MAGNETIC FIELD 

If the conductor of length l, carrying current I is lying inside a magnetic field of intensity B and is making an angle q with it, then force acting on the conductor is given by

F = IlB sin Θ

If the conductor is lying perpendicular to the magnetic field, then

θ = 90° [sin θ = 1] and the force becomes F = IlB.

This force acts in a direction which is perpendicular to the plane containing the conductor and the magnetic field (Fig.) and is maximum.

If the conductor is lying parallel to the magnetic field, then θ = 0° (sin θ = 0) and the force becomes zero and is minimum.

Fleming's Left Hand Rule 

If the forefinger, second finger and thumb of the left hand are stretched at right angles to each other, with the forefinger in the direction of the field and the second finger in the direction of the current then the thumb indicates the direction of the force. 

Factors on which the force acting on the current carrying conductor depends

The force acting on a current carrying conductor is placed in the magnetic field depends upon :

(i) The strength of the magnetic field : If the conductor is placed in a strong magnetic field, it experiences a large force. That is, F∝ B (strength of magnetic field)

(ii) The strength of the electric curent : If large current flows through the conductor placed in the magnetic field, it experiences a large force. That is F ∝ I.

(iii) The length of the conductor : A long conductor experiences a greater force than the short conductor, when placed in the magnetic field. That is, F ∝ ℓ.

That is F∝ BIℓ

or F = kBIl

If k = 1, F = BIℓ

then B =

If I = 1amp. and l = 1m then B = F

Thus, magnetic field strength (B) is defined as the force acting per unit current per unit length of a conductor placed perpendicular to the direction of the magnetic field.

SI unit of magnetic field strength is Tesla.