Force and pressure. — Science STD 8 — Question

Explain why, sometimes when we take off the woollen sweater or a polyester shirt in a dark room, we can see tiny sparks of light and hear a crackling sound.

A ray of light is incident normally (perpendicularly) on a plane mirror. Where will this ray of light go after reflection from the mirror?

Name one animal disease each caused:

1. By virus.
2. By bacteria.
3. By fungus.

What happens when a beam of sunlight is passed through a glass prism?

What will you observe when the metal top of an electroscope is touched with a glass rod which has been rubbed with silk cloth? Give reason for your answer.

What is a ‘combine’ which is used in agriculture? State its functions.

Name the member of the Solar System which appears in the sky like a bright ball of light with a long glowing tail.

Name two non-contact forces.

What are the two ways in which farmers store food grains?

Where is the lower end of the lightning conductor fixed and how?