A mechanism is an assemblage of

Solution (By Examveda Team)

Definition:
A mechanism is a combination of rigid bodies, known as links, connected by joints in such a way that they produce a desired motion when one of the links is given an input motion. The purpose of a mechanism is to convert input motion into a specific output motion.

Correct Answer: Option C – Four or more than four links

Explanation:
In the theory of machines, a mechanism must be able to produce definite relative motion between its parts. For this to be possible, at least one link must be fixed, and the remaining links must be capable of moving in a controlled manner.

According to Gruebler’s criterion for planar mechanisms, a mechanism generally requires a minimum of four links. When four or more links are connected in such a way that one is fixed and others can move, they form a kinematic chain, and if that chain is closed and at least one link is fixed, it becomes a mechanism.

Therefore, a mechanism is typically defined as an assemblage of four or more links that transforms input motion into a controlled output motion.

Why other options are incorrect:
Option A: Two links – Two links connected by a joint form a single pair, not a mechanism. It cannot produce a constrained output motion by itself.
Option B: Three links – Three links connected together form an incomplete kinematic chain and are generally not capable of producing definite motion without adding a fourth link.
Option D: All of these – This is incorrect because only Option C meets the proper condition for forming a mechanism.

Conclusion:
A mechanism requires at least four links to produce constrained and useful motion. Hence, the correct answer is Option C.