Question

Which rule is used to find the direction of magnetic field in a toroid?
A. left-hand thumb rule
B. right-hand thumb rule
C. both A and B
D. neither A or B

Answer 1

A toroid is basically a solenoid which has been bent into circular shape. In a toroid, we have current flowing through the toroid in a circular direction and the magnetic field will be decided by one of the given laws. By studying the flow of current in the toroid, we can find the correct answer.

Complete step-by-step answer:
A toroid consists of several turns of coil wound around each other and the whole coil is shaped in a circular way. A toroid is basically a solenoid which has been bent into circular shape. The current flows through the coil producing a magnetic field. Now in order to find out the direction in which the magnetic field is produced by a toroid, we will need to use the right hand thumb rule.
The right hand thumb rule states that if we hold the right hand with fingers curled and the thumb pointing then the curl of fingers represents the direction of flow of current and the direction in which the thumb points is the direction of the magnetic field produced by that current.
Based on this, in case of a toroid which is circular in shape, if the current is flowing in anticlockwise direction then the direction of the magnetic field is perpendicular to the plane of paper directed upwards.
Hence, the correct answer is option B.

So, the correct answer is “Option B”.

Note: It should be noted that we can reverse the quantities that we use in the right hand thumb rule. It can also be given as that if we hold the right hand with fingers curled and the thumb pointing then the direction in which the thumb points represents the direction of flow of current and the curl of fingers represents the direction of the magnetic field produced by that current.