Question

Identify the direction of the magnetic field in the region shown in the figure above.
(A) Out of the page and perpendicular to it.
(B) Into the page and perpendicular to it.
(C) Toward the top of the page.
(D) Toward the bottom of the page.
(E) To the right.

Answer 1

Hint:"The Left-Hand Rule" determines the force direction acting on the conductive material in a magnetic field when the direction of the magnetic field and the direction of current being supplied are known. By using this rule, we can determine the direction of the magnetic field in the region shown in the figure.

Complete step by step answer:
Given: A region where the magnetic field is acting in such a way that it makes a point A in the magnetic field to move in a vertical circular motion.
Now, in order to keep the point A moving in the circular motion, there is a magnetic force that is being applied by the magnetic field. Since the force is keeping point A in a circular motion, it is also known as the Centripetal Force, and the direction of this centripetal force is always radially inwards.So, in the figure given above, the position of the point A is at the top of the circle, then the direction of the net force acting on this point would be downwards.
Now, by applying the "Left-Hand Rule" also known as the "vector product rule" in this
condition, we can determine the direction of the magnetic field.This representation of the rule shows us the direction of the force being applied on the conductive material with respect to the direction of the magnetic field and the direction of the current supplied.
Therefore, the direction of the magnetic field in the region is –
(A) Out of the page and perpendicular to it.

Note: If the mass of point A is taken under consideration, then the direction of the net force acting on the point would be downwards, same as before. Because the forces acting on the Point A with their respective directions are-
(i) The Centripetal Force – Direction is radially inwards, but since point A is at the top, then this force's direction would be downwards.
(ii) Weight of Point A – This force's direction is always the direction of gravity, which is downwards.