Tag: transfer of heat

Questions Related to transfer of heat

Why is electrical wiring usually made from copper?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Because copper is shiny.

  2. Because copper conducts electricity.

  3. Because copper is not magnetic

  4. none of these

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Correct Option: B
Explanation:

Copper is usually used for copper wiring because copper conducts electricity. Because electrical conductivity of copper is good enough and it is cheap too. So it is used in wiring.

Which of the following materials is an electrical conductor?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Silver

  2. Silver-coloured plastic

  3. Cork

  4. Rubber

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Correct Option: A
Explanation:
As we know that generally, metals are conductors and non-metals are insulators. That is metal conduct electricity more than that of non-metal.
SIlver is the only metal present in the list, so it is the only electrical conductor.
All others are non-metals.

Which of the following materials is an electrical insulator?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Aluminium

  2. Gold

  3. Rubber

  4. all of these

Show answer
Correct Option: C
Explanation:
As we know that generally, non-metals are insulators and metals are conductors.
As rubber is the only non-metal in the list, so it is an electrical insulator.

Why are insulators important in an electrical circuit?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. They make the circuit safe to touch.

  2. Electricity will only flow through insulators.

  3. Light bulbs and buzzers are only made of insulating materials.

  4. All of the .above

Show answer
Correct Option: A
Explanation:

Insulators are used in circuits, as they don't conduct electricity, they are used for insulation of wire, switches, plugs, etc. So that circuit could be made shock free and safe to touch.

Why are electrical plugs made of plastic?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Plastic is stronger than all other materials.

  2. Plastic is a good electrical conductor.

  3. Plastic protects people from electricity.

  4. Only plastic can be made into the right shape for a plug

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Correct Option: C
Explanation:

Electrical plugs are made up of plastic because plastic protects people from electricity. As we know that plastic is an electrical insulator readily available and cheap. So as to make the plugs shock free, they are made up of plastic.

Why is electrical wiring usually covered with a layer of plastic?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. To make it look pretty

  2. To help electricity flow along the wire

  3. To make it safe

  4. none of these

Show answer
Correct Option: C
Explanation:

Electrical wiring is usually covered with layer of plastic to make it safe. As we know that plastic is an electrical insulator and it is readily available and cheap. So as to insulate the electricity carrying wire, to make it shock free. It is covered with layer of plastic.

A material that does NOT let electricity pass through it is called ...

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. an electrical conductor

  2. an electrical insulator

  3. an electrical appliance

  4. none of these

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Correct Option: B
Explanation:
A material that does not allow to electricity to pass through, it is called an electrical insulator.
They do not have free electrons present in their outer most shell which would work as charge carriers for conduction of electricity.

Materials that allow electrons to flow through them are known as

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Insulator

  2. Conductors

  3. Electrolytes

  4. Bases

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Correct Option: B
Explanation:

Materials that allow electrons to flow through them are known as conductors because they consist of free electrons.

Which of these is a good electrical conductor?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Water

  2. Sweat

  3. The human body

  4. All of the above

Show answer
Correct Option: D
Explanation:
Water is a good electrical conductor but not distilled water. Tap water, Sea water, rain water etc. conduct electricity as they consists of impurities; salts of $Ca, \; Mg,\; Na$ which behave as charge carriers.

Sweat conducts electricity although it is mainly water, it still consists of lot of minerals, lactic acid, urea; in short, it is an ionic liquid (electrolyte)

Human body consists of $75 $% of water and also consists of many minerals and salts. So human body also conducts electricity.

State whether given statement is True or False
In a superconductor, electricity will flow for a long time and then stop.

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. True

  2. False

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Correct Option: B
Explanation:
False
Superconductors are those materials which have exactly zero resistance and expulsion of magnetic flux occurs when they are cooled below certain temperatures.