To find out magnetic field around a wire carrying electric current take a wire and pass it through the centre of a horizontal sheet of cardboard. Connect the ends of wire to a battery. Sprinkle some iron fillings on the cardboard sheet and switch on the circuit to pass electric current through the wire. Now, tap the cardboard gently. On tapping, you will observe that the iron fillings arrange themselves around the wire in concentric circles. These concentric circles of iron fillings around the current carrying wire represent the magnetic field.
If the current flows through the wire form A to B then the direction of magnetic lines of force is anticlockwise. On the other hand, if the current flows through the wire B to A then the direction of magnetic lines of force is clockwise.
The direction of magnetic field produced by current carrying wire can be found by Maxwell’s right hand thumb rule.
Test Your Understanding and Answer These Questions:
- How can you prove experimentally that the magnetic field produced around a conductor is associated with current passed through it?
- How can you found the direction of magnetic lines of force produced by a straight current carrying conductor?