Question

Which of the following determines the direction of the magnetic field due to a current-carrying conductor?
(A) Faraday’s law of electromagnetic induction
(B) Fleming’s left-hand rule
(C) Lenz’s rule
(D) Maxwell’s corkscrew rule

Answer 1

Hint
The direction magnetic field due to a current-carrying conductor can be determined using various rules such as Fleming’s right-hand rule and Maxwell’s corkscrew rule.

Complete step by step answer
According to Maxwell’s corkscrew rule or right-hand screw rule, the direction of magnetic lines of force can be determined in association with the direction of the current. Consider a right-handed screw being placed along the direction of current-carrying linear wire such that it is rotated downward in the direction of the current. When the screw is rotated downward, then the direction of the right-handed rotation of the screw will depict the direction of the magnetic field lines as shown in the figure.

Therefore, (D) Maxwell’s corkscrew rule is the correct answer.

Additional information
The direction of the magnetic field can also be determined using Fleming’s right-hand rule. According to this rule, the fingers of the right hand are stretched such that the thumb, forefinger, and the middle finger are placed perpendicular to each other. If the thumb points in the direction of the motion of the current-carrying conductor and the middle finger depict the direction of the current, then the forefinger will give the direction of the magnetic field as shown in the figure.

Note
Electric fields can be determined when the charge is in rest. However, the magnetic field can be determined when the charge is in motion. It cannot be determined in the rest position of the charge.