AQA P1:1 (to finish)

Infrared radiation is energy transfer by electromagnetic waves.

The hotter the object, the more infrared radiation it emits in a given time.

All objects emit infrared radiation.

Infrared radiation is part of the electromagnetic spectrum

The sun emits all types of electromagnetic radiation.

The Earth's atmosphere blocks out most harmful radiation.

The Earth's atmosphere is described as a greenhouse because:

• It allows short wavelength infrared radiation in, warming objects up
• The heat emitted by the warmed objects isn't let back out because the wavelengths are too long, so the Earth warms up.

Carbon dioxide, methane and water vapour contribute to the greenhouse effect

The increased temperature due the greenhouse effect is increasing sea levels as polar ice caps melt into the oceans.

Dark, matt surfaces are the best emitters of infrared radiation

Shiny, light surfaces are the best reflectors of infrared radiation

A shiny, light thermal blanket would keep an accident survivor warmest

Matt surfaces absorb more radiation than shiny surfaces because there are lots of cavities to trap the radiation, whereas it bounces off the smooth surface of shiny objects.

The three states of matter are solid, liquid and gas

Liquids and gases are fluid

Solids have a fixed shape

Liquids and solids have a fixed volume

Gases have the lowest density

We can change the state of a substance by heating or cooling it.

When a kettle is boiled, the water evaporates into steam, a gas.

When dry ice (solid CO2) warms up, it becomes a gas directly from a solid.

Condensation is when a gas turns into a liquid through cooling.

Solids, liquids and gases are made up of particles.

The particles move faster when the temperature of the substance is increased.

Particles are arranged in a fixed pattern in a solid.

Particles in a liquid are unfixed, but still in contact with eachother.

Particles in a gas are generally much further apart from one another.

Metals are the best material for conduction.

Wood conducts better than glass.

Wool and fibreglass are good insulators because they contain trapped air (an insulator) between the fibres.

Free electrons move around in a metal at random, colliding with eachother and with the positive ions in the metal.

When a metal rod is heated, the free electrons at the heated end gain kinetic energy.

The free electrons transfer this energy from the hotter end to the cooler end by moving faster, diffusing and colliding more with the cooler electrons and ions.

In a non-metallic solid, all the electrons are contained in the atoms.

In a non-metallic solid, conduction only happens due to vibrating atoms, which is much less effective than conduction in a metal.

Convection is