State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it and (iii) current induced in a coil due to its rotation in a magnetic field.

Explanation

(i) The direction of magnetic field produced around a current-carrying conductor is given by right hand thumb rule. If the conductor carrying current is held in the right hand in such a way that the thumb points in the direction of current, then direction of curl of fingers gives the direction of the magnetic field.
(ii) The direction of force experienced by a straight conductor carrying current placed in a magnetic field, which is perpendicular to it is determined by Fleming.s left hand rule. Hold the thumb and first two fingers of the left hand at right angles to each other with the first finger pointing in the direction of the Field and the second finger in the direction of the current, then the thumb points in the direction of the motion.
(iii) The direction of current induced in a circuit by changing magnetic flux due to motion of a magnet is determined by Fleming.s right hand rule. If we stretch our right hand in such a way that the thumb, forefinger and central finger remain perpendicular to each other, so that the forefinger indicates the direction of the magnetic field and the thumb in the direction of motion of conductor, then the central finger indicates the direction of induced current.