Describe how you could demonstrate that white light is composed of a number of colours.

A star sometimes appears brighter and some other times fainter. What is this effect called? State the reason for this effect.

Which is refracted most by a prism: red light or violet light? Explain why?

What happens when a beam of sunlight enters a dusty room through a window? Explain your answer.

The eyes of a person are focused

1. On a nearby object, and
2. On a distant object, turn by turn. In which case:

1. The focal length of ye-lens will be the maximum?
2. The converging power of eye-lens will be the maximum?

Why do stars twinkle?

What will happen if another similar glass prism is placed upside down behind the first prism?

Draw a ray diagram to show the refraction of light through a glass prism. Mark on it,

1. The incident ray,
2. The emergent ray,
3. The angle of deviation.

A student sitting in the last row of the class-room is not able to read clearly the writing on the
blackboard.

1. Name the type of defect he is suffering from.
2. How can this defect by corrected?

Why do we observe random wavering or flicking of the objects near a fire or on a very hot day?