Light, Shadows and Reflections

We need (a)   to see the things around us.

All the sources of light can be classified into (a)   categories.

An object that gives out its own light is called (a)  

We can see the moon because it reflects (a)   into our eyes.

Light travels in (a)   lines.

The property of light by which it travels in straight lines is called. (a)   propagation of light.

An (a)   substance on which shadow is formed called a screen.

Shadow is formed in the direction (a)   to the source of light.

The shape and size of the shadow varies with the (a)   of the source of light.

(a)   eclipse occurs when the sun, the moon and the earth come in a straight line.