Question

State condition when magnitude of force on a current carrying conductor placed in a magnetic field is zero.

• A. When current in conductor is in the direction of magnetic field.
• B. When current in conductor is perpendicular to the direction of magnetic field.
• C. Always zero
• D. None of these

Answer 1

The correct option is A When current in conductor is in the direction of magnetic field.

The force on a charged particle moving in a magnetic field is at its maximum when the particle is moving at right angles to the direction of the magnetic field and zero when the particle is moving parallel to the field. The direction of the drift velocity of electrons in a conductor is along the length of the conductor.

Thus, the magnitude of the force on a current-carrying conductor in a magnetic field varies with the angle between the direction of the length of the conductor and the direction of the magnetic field.
Hence, the magnitude of force is zero when the conductor lies parallel to the field.