Answer:

1. The luminous objects are visible as they emit light on their own. The non-luminous objects are visible because of luminous objects. The sun and candle are the two examples.

2. Luminous objects are objects that generate their own light. Illuminated objects are objects that are capable of reflecting light to our eyes. The sun is an example of a luminous object, while the moon is an illuminated object. Non-luminous objects are the objects that do not have their own source of light energy and hence they cannot emit light and are not responsible for vision. These objects can only be visible due to luminous objects. Examples of non-luminous objects are the moon, plants, and spoons.

3. Objects that can emit light energy by themselves are known as luminous objects. Objects that cannot emit light energy by themselves are known as non-luminous objects. These objects can cause a sensation of light. These objects do not cause the sensation of light.