Radiation Flashcards
Which type of radiation is felt as heat?
infrared
What type of objects absorb and emit the most radiation?
objects with dark, matt surfaces
What type of objects absorb and emit the least radiation?
objects with light, shiny surfaces
If an object is cooling, how much radiation is it absorbing compared to the amount that it is emitting?
It is emitting more than it is absorbing
What is a perfect black body?
An object which absorbs all radiation, and doesn’t reflect or transmit any radiation.
When an object is heated, what happens to the amount of radiation emitted and the peak intensity?
the amount of radiation is higher at all wavelengths, and the peak intensity is at a shorter wavelength
What is the wavelength of the radiation coming to earth from the sun relative to the wavelength of radiation being emitted by the earth?
shorter
How does the ice caps melting speed up global warming?
It makes a darker surface which reflects less radiation from the sun, so less radiation escapes earth.
What effect to clouds have on the amount of radiation entering and leaving the atmosphere?
They reflect radiation from the sun away from earth, decreasing the amount of radiation which reaches earth, but they also reflect radiation from the earth’s surface back at the earth, heating it up
What is the doppler effect?
When the pitch of a sound increases as the source moves towards you and decreases as the source moves away from you
How is the doppler effect caused?
When the source of a wave moves towards you, the waves are compressed, increasing the frequency and decreasing the wavelength, and when the source of a wave moves away from you, the wave is stretched, decreasing the frequency and increasing the wavelength
What is red shift?
When objects move away from earth very quickly, so the waves are stretched and the wavelength increases, making it redder.
How does red shift give evidence for the big bang?
Distant objects are moving away from us, and the speed at which an object is moving and its distance from us are directly proportional, so in the past everything in the universe must have been very close together, and the universe is now expanding.
