Q. Which of the following is a non-contact force ?

Correct Answer: a) Magnetic force

Explanation:

A non-contact force is a force that acts on an object without any physical contact between the objects.

– Magnetic force (Option a): Magnetic force is a non-contact force because it can act at a distance. For example, a magnet can attract or repel another magnet or magnetic material without touching it.

– Frictional force (Option b): Frictional force is a contact force because it arises when two surfaces are in physical contact and resist motion relative to each other.

– Impact force (Option c): Impact force is also a contact force because it occurs when two objects physically collide with each other.

– None of these (Option d): This is incorrect because magnetic force is indeed a non-contact force.

Thus, the correct answer is a) Magnetic force.