LEARNATHON
III

Competition for grade 6 to 10 students! Learn, solve tests and earn prizes!

### Theory:

According to H.A.Lorentz, a charge moving in a magnetic field in a direction other than the magnetic field's direction experiences a force. It is called the magnetic Lorentz force. A current is formed by moving charges. A conductor carrying moving charges in a magnetic field that is not in the same direction as the magnetic field will experience a force and cause motion in the conductor.

Consider the following activity to understand better the force acting on a current-carrying conductor.
• Thread a perpendicular wire through a piece of cardboard.
• Make sure the wire is connected in such a way that current flows up it.
• Turn the circuit on.
• Allow the current to run its course.
• Mark the position of a magnetic compass on the cardboard.
• Now move the magnet to a new location and mark it.
• If you join all the points, you will find that it is a circle.
• Reverse the direction of the current; you will find the magnetic circles are clockwise.
Deflection of current-carrying wire in a magnetic field

From this activity, we can deduce that a current-carrying wire has a magnetic field perpendicular to the wire (by looking at the deflection of the compass needle in the vicinity of a current-carrying conductor). The compass needle is deflected, indicating that the current-carrying conductor is exerting a force on it.

In $$1821$$, Michael Faradaydiscovered that when a current-carrying conductor is placed in a magnetic field, it is also deflected. The permanent magnet's magnetic field interacts with the magnetic field produced by the current-carrying conductor, resulting in a force on the conductor.