Question

What is a convergent beam of light?

Answer 1

Hint: The word converges or convergent in science generally means meeting or joining of objects or bodies at a point or plane. Therefore, it can be deduced that a convergent beam of light means a beam of light, whose individual rays keep on coming closer constantly and finally meet at a point.

Complete step by step answer:
When light rays from different points constantly keep coming closer together and finally meet at a point, then the light beam is known as a convergent beam of light. As the beam of light keeps travelling in space, its coverage area keeps on decreasing. This is an obvious property of a convergent beam of light.
Convergent beams of light are produced in general by convex lenses and concave mirrors.

Additional information:
An interesting experiment that students can perform easily to understand convergent beams of light is by using a simple magnifying glass (a convex lens), a piece of paper and sunlight. Hold the magnifying glass in such a way, so that the sun’s rays fall on it and converge onto a point on the ground. Keep a paper on this point and the paper will slowly heat up and may even catch fire. A simple paper kept in the sun will not catch fire, but due to the magnifying class a concentrated convergent beam focuses all the heat energy on the paper.

Note: Students can keep in mind that convex lenses and concave mirrors produce convergent beams of light by thinking or actually performing the experiment described above. The experiment can also be performed with a concave mirror, but a few tweaks will have to be made. The paper will have to be held above the mirror, between the sun and the mirror.
Many students get confused between the converging and diverging effects of the different kinds of lenses and mirrors. However, by thinking of the experiments and their results, a lot of scope for confusion can get eliminated.