(a) Draw a sketch to show the magnetic lines of force due to a current-carrying straight conductor.
(b) Name and state the rule to determine the direction of magnetic field around a straight current-carrying conductor.
(a)
(b) Maxwell's right-hand thumb rule: According to this rule, imagine that you are grasping the current- carrying wire in your right hand so that your thumb points in the direction of the current, then the direction in which your fingers encircle the wire will give the direction of the magnetic field lines around the wire.