Question

The picture below shows a wire carrying conventional current out of the page (or screen), producing a magnetic field around the wire. Which table gives the correct dimensions for the magnetic field at the two positions around the wire?

(A)

| Direction of the field
---|---
Right of the wire| Toward right of the page
Left of the wire| Toward bottom of page

(B)

| Direction of the field
---|---
Right of the wire| Toward left of the page
Left of the wire| Toward top of page

(C)

| Direction of the field
---|---
Right of the wire| Toward top of the page
Left of the wire| Toward right side of page

(D)

| Direction of the field
---|---
Right of the wire| Toward lower left portion of page
Left of the wire| Toward upper right of page

Answer 1

Hint : In order to solve this question, we are going to use the Right hand’s thumb rule, which is a rule for getting the direction of the magnetic field around a current carrying conductor at any point near it. After using the rule, we get the magnetic field direction along the right and the left sides of the wire.
According to the Right hand’s thumb rule, if you point your pointer finger in the direction the positive charge is moving, and then your middle finger in the direction of the magnetic field, your thumb points in the direction of the magnetic force pushing on the moving charge.

Complete Step By Step Answer:
In order to find the direction of the magnetic field, we are going to use the Right Hand’s Thumb rule, which is a very basic rule to find the direction of the magnetic field around a current carrying conductor. In the given diagram, as we can see that the current is in the upward direction which gives the direction of the magnetic field as the anticlockwise direction. Now the direction of the magnetic field at any point is given by the tangent to that point. Therefore , the magnetic field about the right side of the wire will be towards the top of the page as given by the right hand’s rule while for the point at the left of the wire, it will be toward the right side of the page.
Hence, option (C) is the correct answer.

| Direction of the field
---|---
Right of the wire| Toward top of the page
Left of the wire| Toward right side of page

Note :
This rule is based on the underlying that relates the magnetic field and the forces that they exert on the moving charges. Note that the two points are taken separately and the magnetic field around that point is taken. This law is applicable on all the current carrying conductors and moving charges.