Right Hand Thumb Rule

The right hand thumb rule gives the direction of a magnetic field developed around a current carrying wire. If you hold a current carrying wire in your right hand with your thumb pointing in the direction of current, then the direction in which your fingers curl indicates the direction of the magnetic field lines of force.

If current is flowing vertically upwards the direction of the magnetic field will be anti-clockwise around the wire. A tangent drawn at any point on this circular field pointing in the direction of the magnetic field gives the magnetic field direction at that point.

Example-

Take a wire and place it north-south let current flow from south to north and place a magnetic needle below the wire. The direction of magnetic field formed due to the current will be towards west below the wire hence the magnetic needle will deflect towards the west.

This is also known as SNOW rule. When direction of current is South to North and wire is Over the compass the magnetic needle deflects West.

If one change is made in this order (say, compass kept over the wire) then deflection changes from West to East. If two changes are made (say, compass kept over the wire and direction of current changed to North to South) then deflection remains to West.

REFER TO THE GAME VIDEO FOR ALL SOLUTIONS

By convention, in a circuit the direction of current is from positive terminal to negative terminal. The electrons actually flow in the opposite direction.

FLEMING’S LEFT HAND RULE

When a current carrying wire is placed in an external magnetic field a force is exerted on the wire. The direction of the force exerted is give by Fleming’s left hand rule.

If you hold the thumb, forefinger and middle finger of your left hand such that they are all at right angle to each other and forefinger points in direction of the magnetic field and the middle finger points in the direction of the current in the wire, then the direction in which the thumb is pointing becomes the direction of the force exerted on the wire.

By convention, in a circuit the direction of current is from positive terminal to negative terminal. The electrons actually flow in the opposite direction.

REFER TO THE GAME VIDEO FOR ALL SOLUTIONS