Question

What can you see in a completely dark room ? If you switch on an electric bulb in this dark room as a light source, explain how you could now see : (a) the electric bulb. (b) a piece of white paper.

Answer 1

We cannot see anything in a completely dark room.
a.) We can see the light bulb as it emits lights, the light from the bulb enters our eyes and we are able to see it.
b.) We can see the paper because of the light reflected by it, it does not have it's own light but it reflects the light emitted by the bulb.