Why do dust particles in a beam of sunlight appear to sparkle?

In this thread, i would like you to comment on the nature of light and how operation of telescopes. light has a duality of a particle and a wave; which one affects your life? also how does light interact with optics inside telescopic systems? answer these questions in two paragraphs. then respond the another students response.

Another word for electromagnetic energy is a. heat b. force c. matter d. radiation

Four friends, a, b, c, and d are standing varying distances away from a speaker which is producing sound waves.