Conductors and Insulators

Q.

What is electric susceptibility of dielectric material?

Q.

Why is electrical wiring usually made from copper?

1. Copper is a non-magnetic material

2. Copper is shiny

3. Copper can be insulated easily.

4. Copper is a good conductor of electricity

Q. Why conductors allow electric current to pass through them and insulators don't?

Q.

What type of materials allows electricity to flow freely?

1. conductors

2. insulators

3. Wood

4. Copper

Q.

Lead is a good conductor of electricity.

1. True
2. False

Q.

Name a metal which

(d) is the poorest conductor of electricity.

Q.

An example of a poor conductor of electricity is

1. copper

2. silver

3. aluminum

4. pure water

Q. Which of the following is a poor conductor of electricity?

1. Lemon juice
2. Vinegar
3. Vegetable oil
4. Sea water

Q.

Copper is a conductor but plastic coating is an insulator

1. True
2. False

Q.

Write true or false for each statement:

(a) A fuse wire has a high melting point.

(b) Flow of protons constitutes electric current.

(c) A fuse wire is made of silver.

(d) S.I. unit and commercial unit of electrical energy are same.

(e) Overloading of electric current in circuits can lead to short circuiting.

(f) Our body can pass electricity through it.

(g) The metallic cases of all appliances are insulators of electricity.

(h) The earth wire protects us from an electric shock.

(i) A switch should not be touched with wet hands.

(j) All electrical appliances in a household circuit work at the same voltage.

(k) In a cable, the green wire is the live wire.

(l) A fuse is connected to the live wire.

(m) A switch is connected to the neutral wire.

Q. Mercury is a/an ______ of electricity, and pure water is a/an ______ of electricity.

1. insulator; insulator
2. insulator; conductor
3. conductor; insulator
4. conductor; conductor

Q.

Why is electrical wiring usually made of copper, not silver?

1. Copper is a better conductor than silver.

2. Copper is less magnetic compared to silver

3. Copper is less expensive than silver.

4. None of these

Q.

How does electric discharge in lightning occurs if air is a bad conductor?

Q.

Select non-conductors of electricity from the following

1. Water

2. Pure water

3. Rubber

4. Paper

Q.

Question 17

If air and cloud were good conductors of electricity, do you think lightning could occur? Expalin.

Q.

Which material lose electrons when 2 material ( insulators) are rubbed together to form electrostatic force?

Q.

Why do electricians wear rubber gloves?

1. They are inexpensive.

2. They are waterproof.

3. They are insulators.

4. They are soft.

Q.

Is Ebonite A Dielectric?

Q. Question 8 (iii)
Fill in the blanks.
(c) Small amount of a mineral salt present naturally in water makes it a ___ of electricity.

Q.

The electrical charge can be transferred from a charged object to another through

1. Vacuum

2. an insulator

3. a conductor

4. Air

Q.

Is Copper a dielectric?

Q.

Which of the following are true for a conductor?

1. Charges mainly travel through the surface of the conductor

2. A conductor doesn't have any free electrons

3. Charges travel through the entire body of the conductor

4. Charges tend to stay at the point of initial contact

Q. Which of the following is a bad conductor of electricity?

1. Tap water
2. ORS drink
3. Distilled water
4. Salt water

Q. Which of the following statement(s) is/are NOT correct?

1. Metals are good conductors of electricity.
2. Free electrons in an insulator enable them to conduct electricity through them.
3. Copper is a bad conductor of electricity.
4. Insulators do not allow electricity to pass through them.
   

Q. All liquids conduct electricity.

1. False
2. True

Q.

The polarized dielectric is equivalent to

Q.

Rubber is an example of an insulator.

1. True
2. False

Q. Lemon is a good conductor of electricity because it contains ________.

1. acid
2. base
3. salt
4. metal ions

Q. Question 17
Observe the following circuits carefully. In which circuit will the bulb glow. Write ‘Yes’ or ‘No’ in the blank space provided along each of the circuit given in the figure.

Q.

Can a dielectric conduct electricity