Conduction, Convection, Radiation

What is conduction?

The transfer of energy between particles through direct contact.

How is energy transferred by conduction?

Particles transfer energy to neighbouring particles through direct contact.

Why are metals effective conductors?

Their free-moving electrons allow energy to be transferred quickly.

What is convection?

The transfer of thermal energy through the movement of liquids or gases.

Where can convection occur?

In liquids and gases.

What happens to a fluid when it is heated?

Its particles move faster, spread further apart, its density decreases, and the fluid rises.

What happens to a fluid when it is cooled?

Its particles move slower, become closer together, its density increases, and the fluid sinks.

Why does heated fluid rise?

Heating causes its particles to spread further apart, decreasing its density.

Why does cooled fluid sink?

Cooling causes its particles to become closer together, increasing its density.

What is radiation?

The transfer of thermal energy by electromagnetic waves.

What makes radiation different from conduction and convection?

Radiation does not require a medium and can travel through a vacuum.

What are the three methods of thermal energy transfer?

Conduction, convection and radiation.

How does conduction differ from convection?

Conduction transfers energy through direct contact, while convection transfers energy through the movement of liquids or gases.

How does radiation transfer energy?

Through electromagnetic waves.

Which method of heat transfer requires direct contact?

Conduction.

Which method of heat transfer involves moving liquids or gases?

Convection.

Which method of heat transfer can travel through a vacuum?

Radiation.

What is the sequence for convection when a fluid is heated?

Particles move faster → spread further apart → density decreases → fluid rises.

What is the sequence for convection when a fluid is cooled?

Particles move slower → become closer together → density increases → fluid sinks.

How does heat from the Sun reach Earth?

Through radiation.

Why can heat from the Sun travel through space?

Radiation does not require a medium and can travel through a vacuum.

What happens when a metal spoon is placed in hot water?

Thermal energy is transferred through the spoon by conduction.

Why does warm air rise?

Heating makes the air less dense, causing it to rise.

Why does cool air sink?

Cooling makes the air denser, causing it to sink.

Why do convection currents occur?

Differences in temperature cause differences in density, causing warmer fluid to rise and cooler fluid to sink.

Why does a road or bridge expand on a hot day?

Heating makes its particles move or vibrate more and generally become further apart, causing the material to expand.