Light — Science STD 7 — Question

Shine light from the torch placed at 1.5 m , on the globe in a dark room and record your observation. State how day and night occur on the earth due to its rotation on the basis of your observation.

Life would be impossible without plants. Explain, how?

Three statements are provided here which define the terms, i.e. sludge, sewage and wastewater. Pick out the correct definition for each of these terms.
(i) The settled solids that are removed in wastewater treatment with a scraper.
(ii) Water from kitchen used for washing dishes.
(iii) Wastewater released from homes, industries, hospitals and other public buildings.

Observation : Table : Conduction of electricity by different objects or materials

Object/ Material	Observation (bulb glows/ does not glow)	Good conductor of electricity or poor conductor of electricity
Piece of aluminium foil	Bulb slows	Good conductor of electricity
Iron nail	Bulb slows	Good conductor of electricity
Lump of sulphur (peasized)	Bulb does not glow	Poor conductor of electricity
CooDer wire	Bulb slows	Good conductor of electricity
Piece of coal	Bulb does not glow	Poor conductor of electricity
Piece of dry wood	Bulb does not glow	Poor conductor of electricity
Stone	Bulb does not glow	Poor conductor of electricity

How water and nutrients absorbed by the root are transported to the leaves?

You are given three mirrors of different types. How will you identify each one of them?

List two differences between conductors and insulators.

How nutrients are replenished in soil?

An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire. Would you agree? Give reasons for your response.

At a camp site, there are tents of two shades – one made with black fabric and the other with white fabric. Which one will you prefer for resting on a hot summer afternoon? Give reason for your choice. Would you like to prefer the same tent during winter?