P2 Energy transfer by heating

What is a conductor?

A material which readily allows energy or charge to pass through it

What is an insulator?

A material that doesn’t readily allow energy or charge to pass through it (a mortal with low thermal conductivity)

What is thermal conductivity?

Material property that determines the energy transfer by conductionWHy

Why do substances expand when heated?

As the particles gain more energy they move more, as they move more they take up more space causing the material to expand

Why do substances contract when cooled?

As the particles lose energy they move less, taking up less space causing the material to contract

When a material expands, what happens to its density?

Becomes less dense

Which states of matter can convection occur in?

fluids (liquids and gases)

What is a convection current?

The warmer(less dense) air rises, cooler air (more dense) falls

Does radiation require particles?

No

Can radiation travel through vacuums?

Yes

True or false: all objects emit and absorb infrared radiation

True

What happens to radiation when it reaches dark or shiny objects?

Dark objects absorb the radiation, shiny objects reflect it

How do you calculate payback time?

Cost/annual savings

What is the specific heat capacity equation?

Change in energy = mass x SHC x change in temperature?

What are the. units for specific heat capacity?

J/Kg(degrees)C

How does thermal conductivity effect the rate of energy transfer in conduction?

Higher thermal conductivity = higher rate of energy transfer by conduction

What happens to the rate of reaction for a hotter body?

A body at a constant temperature is absorbing radiation at the same rate as it is emitting radiation

What does the temperature of the earth depend on?

the rate of absorption, the rate of emission of radiation and reflection of radiation into space

Define specific heat capacity

The amount of energy required to raise the temperature of one kilogram of the substance by one degree celcius