Question

Name the rule that helps in finding the direction of magnetic field produced by a current carrying conductor (wire).
A. Maxwell’s right hand thumb rule
B. Maxwell’s left hand thumb rule
C. Joule’s heating effect
D. Ohm’s law

Answer 1

Hint: A current carrying wire produces a magnetic field around it. To find the direction of the magnetic field, an easy method was given by Maxwell, which is called the Maxwell’s right hand thumb rule. By using this method, the direction of both the current and the magnetic field can be found out when any one of them is known.

Complete step by step answer:
A current carrying wire produces a magnetic field around it. The direction of this magnetic field in 3 dimensional space depends upon the direction of the current. To find out the directions of the magnetic field and the current, Maxwell gave an easy method known as Maxwell’s right hand thumb rule.
The rule states that if we hold the wire in our right hand and wrap our fingers around it in such a way so that the outstretched thumb is inline with the direction of the current, then the direction in which the fingers curl gives the direction of the magnetic field.

This is also known as the corkscrew rule since if the long end of the corkscrew points towards the current, the direction in which it must be rotated to tighten it is the direction of the magnetic field.
Hence, the correct answer is A) Maxwell’s right hand thumb rule.

Note: Students often get confused between Maxwell’s right hand thumb rule and Fleming’s right hand rule. Fleming’s right hand rule gives the directions of the force on a conductor when it carries a current in a magnetic field. It makes use of three fingers. The index, thumb and middle fingers. Students should not get confused between the different hand rules namely Maxwell’s right hand thumb rule, Fleming’s left hand rule and Fleming’s right hand rule and should know the proper functioning and usages of each.