[Physics Form 4] Lighting Up!

1. How are we able to see an object?
   Answer: When enough light falls on the object, incident light rays are reflected from its surface. The reflected light rays then enter our eyes and form an image on the retina. We are able to see the object when the brain interprets the image.
   
   
2. Must light be incident on an object? If objects cannot be seen in a dark room, how are we able to see a lighted bulb in it?
   Answer: A lighted bulb is a primary light source that emits its own light. Hence, its incident light rays directly enter our eyes and form an image. On the other hand, objects that do not emit light rely on the reflected incident light rays to form an image in our eyes. These objects act as secondary sources of light.
   
   
3. Is the moon seen through the reflection of the sun's light that is incident on it?
   Answer: Yes.