State and explain Maxwell’s right hand thumb rule. Answer:

According to Maxwell’s right hand thumb rule, when a current-carrying conductor is held in the right hand, the thumb gives the direction of current and the fingers that have encircled the conductor gives the direction of the magnetic field lines around the wire

Consider a straight current-carrying wire which is held vertically in the upward direction from A to B. The wire is held as in the given figure to find the direction of the magnetic field lines that is produced when the current flows through the wire. The thumb gives the direction of the current. The fingers that are encircled around the wire gives the direction of the magnetic field lines. The direction of the magnetic field lines is in the anticlockwise direction.