MAGNETIC EFFECT OF CURRENT
KICKING WIRE EXPERIMENT
When electric current is passed through a conductor placed in a magnetic field, it experiences a mechanical force. The force due to magnetic field acting on a conductor can be demonstrated by Kicking Wire Experiment.
Kicking Wire Experiment
Take a flexible copper wire AB and suspend it from a rigid support with the help of a flexible joint. Place a U shaped magnet around the lower end B of the wire. In the centre of the U shaped magnet place a vessel filled with mercury in such a manner that the lower end B of copper wire touches the surface of mercury. Now, connect the upper end A of wire with the positive terminal of battery and dip another wire from the negative terminal of the battery in the vessel filled with mercury. In this way the circuit gets completed. Now, insert the key. When the key is inserted, the current flows through the wire from end A to B perpendicular to the magnetic field and the wire is kicked outward. This happens because when current passes through a wire placed in a magnetic field, it experiences a force which jerks it in outward direction. It should be noted that the direction of force acting on a current carrying wire placed in a magnetic field is always perpendicular to both the direction of current and magnetic field.
You will also observe that when the direction of current flowing through wire AB is reversed, the wire will move in inward direction.
Fleming’s Left Hand Rule
The direction of force acting on a current carrying conductor can be easily determined by using Fleming’s left hand rule. According to this rule: stretch the thumb, forefinger and central fingers of your left hand mutually perpendicular to each other so that the forefinger points in the direction of magnetic field and central finger in the direction of current then the direction in which the thumb points gives the direction of force acting on the conductor.
Test Your Understanding and Answer These Questions:
- What is Fleming’s left hand rule?
- Explian kicking wire experiment with the help of a diagram.
- Prove that when a current carrying conductor is placed in magnetic field it experieces a force.