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.
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.
|1. What is the force on a current-carrying conductor placed in a magnetic field?
|2. What is Fleming's left-hand rule?
|3. What is electromagnetic induction?
|4. How does Fleming's left-hand rule relate to electromagnetic induction?
|5. What are some practical applications of the force on a current-carrying conductor in a magnetic field?