Magnetic field is the area in which the magnet can show its influence. The magnetic field varies upon the surrounding and types of magnet used.
The magnetic effect of electric current was introduced by Danish Physicist Christian Oersted in 1820. In his experiment, when current was passed to a wire, the needle placed near it got deflected. The deflection of the needle was opposite to the direction of the current. So, he concluded there is certain relationship between magnetism and electricity. The electric current produces magnetic effect in the space around the conductor.
Direction of magnetic field: The direction of magnetic field is generally determined by right hand thumb rule.
Right hand thumb rule:
According to this rule, When, the right hand is held with the thumb, first finger and second finger mutually perpendicular to each other (at right angles), as shown in figure, then:
- The thumb is pointed in the direction of motion of the conductor.
- The first finger is pointed in the direction of the magnetic field. (north to south)
- The middle finger represents the direction of the induced or generated current (the direction of the induced current will be the direction of conventional current (from positive to negative).
The direction of current and magnetic field also can be determined by Maxwell cork screw rule.