Radiation Flashcards
What process does the sun use to heat the Earth?
The sun can’t use conduction because there isn’t a massive metal pole from the sun to the Earth and the sun can’t use convection because there aren’t strong enough currents between the sun and the Earth. The sun uses the process radiation to heat the Earth.
How is radiation different to conduction and convection?
Radiation uses waves, not particles unlike convection and conduction. Between the earth there is lots and lots of space and in space there is no air which makes it a vacuum. Radiation can occur through a vacuum where there is no air or particles but convection and conduction can’t.
What can we use to observe radiation?
We can see radiation through a thermal imaging or infrared camera. Different cameras have different colour scales (e.g. purple to yellow, the purple bits in the image are emitting less radiation than the white and yellow bits).
What dies emit mean?
Emit means to give out. All objects emit radiation but hotter objects emit more than colder objects
What does absorb mean?
Absorb means to take in. Objects can also absorb radiation.
What can radiation also be referred to as.
Thermal radiation, IR(infrared radiation)
Cricket clothing
White is a bad absorber of radiation and it even tends to reflect the radiation away slightly. The cricketers are out all day in the hot sun and the sun is trying to transfer energy into the cricketers by radiation. The white clothes will only absorb some of that energy whereas if they were all wearing black it would absorb more of that energy and they would get very hot and sweaty since black is a good absorber of radiation.
Solar panels
Solar panels are fixed to the top of buildings or houses and they can be used to generate renewable energy. Solar panels are like the opposite of the clothing of cricketers. When it comes to solar panels they want to absorb as much energy as possible transferred from the Sun. Black is the best absorber and emitter of radiation. So the solar panels are made out of a black surface so that they absorb as much energy from the sun as possible.
Tinfoil food
The best thing to wrap food in when you want it to stay warm in terms of a radiation perspective is tinfoil. This is because silver and shiny surfaces are poor absorbers and emitters of radiation. So when the food is trying to radiate energy out to the surroundings before you will stop that radiation from going out too much. The silver shiny foil even slightly reflects the radiation back in on the food keeping it warmer for longer.
White houses in hot countries
White houses in hot countries. In hot countries people want to stay nice and cool inside the house is because of the heat outside. The Sun is transferring energy down onto the Earth. The best way for people to keep the house is nice and cool is to paint them white because white surfaces are poor absorbers and emitters of radiation. If people painted all their houses black the black houses would absorb a lot more of the radiation from the Sun and it would get very hot inside.
Volleyball uniform
The uniform should be the colour white because white is the worst absorber and emitter of energy. This will allow the players to stay cooler when playing volleyball as they won’t absorb as much energy from the sun in comparison to if they were wearing black.
