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Electroscope

NCERT 8th Class (CBSE) Science: Some Natural Phenomena

Question: Why does a comb rubbed on hair attract pieces of paper?

Answer: The comb on rubbing became gets electrically charged and attract pieces of paper. This is called electrostatic force.

Question: Under what conditions do charges attract or repel each other?

Answer: Like charges repel and unlike charges attract each other.

Question: Why do we say that only repulsion is a sure test of charge on a body?

Answer: A charged body can attract an uncharged body and body with an opposite charge. Thus, repulsion alone is a sure test of whether a body is charged or not.

Question: What do you mean by ‘charging by conduction’? What kind of charge does the body acquire?

Answer: When a neutral object is charged by touching it with a charged body, it is called charging by conduction. The object acquires the same charge as that on the charged body.

Question: What is ‘charging by induction’? What kind of charge does the body acquire?

Answer: When a neutral object is charged by bringing a charged body near it without touching it, it is called charging by induction. The object acquires an opposite charge to that of the charged body.

Question: What is the difference between conductors and non-conductors? Give two examples of each.

Answer: Difference is as follows:

Conductors
Non-conductors
1. Substances which allow electric charges to flow through them are called conductors of electricity.
1. Substances that do not allow electric charges to flow through them are called non-conductors or insulators of electricity.
2. Examples: Metals like iron, copper, aluminium, etc.
2. Examples: Plastic, rubber, wood, etc.

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