Question

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.

Answer 1

Electric currents, such as those employed in electromagnets, and electric fields that change in time generate magnetic fields that surround magnetised objects. Because the strength and direction of a magnetic field can change depending on location, they are characterised as a map that assigns a vector to each point of space, or, more accurately, as a field of pseudovectors (due to the way the magnetic field evolves under mirror reflection).

Complete answer:
(i) Maxwell's right-hand thumb rule: A magnetic field is created around a current-carrying straight conductor. The magnetic field in the direction of the current is indicated by the Maxwell right-hand thumb rule. If the right-hand thumb points in the direction of the current, the magnetic field direction owing to the current is given by the remaining curled fingers of the same hand. The curled fingers will be anti-clockwise while the thumb is up, and the magnetic field will be anti-clockwise as well, and vice versa.

(ii) Fleming's left-hand rule: The force experienced by a current-carrying straight conductor in a perpendicular magnetic field. A force acts on a current-carrying conductor whenever it comes into contact with a magnetic field. Fleming's Left-hand Rule can be used to determine the direction of this force.

(iii) Fleming's right-hand rule: A coil's current is induced by its rotation in a magnetic field. When a conductor linked to a circuit travels in a magnetic field, this rule indicates the induced current direction.

Note: A series of magnetic field lines that follow the direction of the field at each location can be used to view the field. Measurement of the intensity and direction of the magnetic field at a large number of sites may be used to create the lines (or at every point in space). Then, at each place, draw an arrow (called a vector) pointing in the direction of the local magnetic field, with the magnitude corresponding to the magnetic field's strength.