Conductor and Insulators

Q.

Why is the handle of a pressure cooker made of ebonite?

Q. Which of the following is a conductor of heat?

1. Plastic
2. Cotton
3. Wool
4. Aluminium

Q.

A key is made up of metal.

1. True
2. False

Q.

Why are ice blocks wrapped in sawdust or woolen blanket?

Q.

Distinguish between conductors and insulators of electricity.

Q.

Wire gauze ensures uniform distribution of heat.

1. True
2. False

Q.

Select conductor of heat from the following

1. Paper

2. Aluminum

3. Plastic

4. Rubber

Q.

What are insulators?

Q.

Substances which allow electric charge to flow through them are called

1. electrodes

2. insulators

3. diodes

4. conductors

Q. Question 21
Observe the following circuit given in figure.

Current does not flow in the circuit if there is a gap between the two wires. Does it indicate that air is a poor conductor of electricity? Does air never conduct electricity? Explain.

Q.

What are insulators?

Q. Why do cooking vessels usually have copper bottoms?

1. Copper has low melting point
2. Copper is an insulator
3. Copper is a good conductor of heat
4. Cooper is cheap