Insulators, Conductors, & Heat Transfer

What happens to air when it is heated?

• It becomes more dense and sinks.

• It becomes less dense and rises, creating convection currents.

• It remains the same and does not change.

• It cools down and contracts.

Is water a good insulator?

• Yes, water is a good insulator.

• No, water is not a good insulator; it is a conductor of heat.

• Water is a perfect insulator at all temperatures.

• Water can insulate electricity but not heat.

Give an example of convection.

• Boiling water, where hot water rises and cool water sinks.

• Heating a metal rod in a flame.

• Ice melting in a warm room.

• A fan blowing air in a room.

How does a thermos bottle minimize heat transfer?

• By using a vacuum layer to reduce conduction and convection, and reflective surfaces to reduce radiation.

• By using thick glass walls to prevent heat loss.

• By filling the bottle with ice to keep contents cold.

• By using a double-walled design without any insulation.

How does heat transfer in solids?

• Through radiation

• Through convection

• Through conduction

• Through evaporation

Why do metals feel cold to the touch?

• Because they are good insulators of heat.

• Because they are good conductors of heat, quickly transferring heat away from your skin.

• Because they have a low density.

• Because they are always at a lower temperature than the skin.

What is radiation?

• The transfer of heat in the form of electromagnetic waves.

• A type of sound wave that travels through air.

• The process of converting light into energy.

• A method of cooling objects by removing heat.

What is the role of insulators in electrical devices?

• Insulators allow electricity to flow freely, enhancing device performance.

• Insulators prevent the unwanted flow of electricity, protecting users from electric shock.

• Insulators are used to increase the temperature of electrical components.

• Insulators help in amplifying electrical signals.

What materials are good insulators?

• Rubber

• Metal

• Wood

• Glass

What is convection?

• The transfer of heat through the movement of fluids (liquids or gases).

• The process of heat transfer through direct contact between materials.

• The transfer of heat through electromagnetic waves.

• The movement of air caused by temperature differences.