P7 Page 14 Flashcards
What is the peak frequency?
Hot objects always emit more of one frequency than any other, this is called the peak frequency.
What is a continuous spectrum?
A continuous range of frequencies emitted form stars.
What does the peak frequency depend on?
Depends on the temperature of the object, the higher the temperature, the more energy the photons radiated will have this a higher peak frequency.
On a continuous spectra red means what?
Red= has low frequency= a cool star
On a continuous spectra what does blue mean?
Blue= has a high frequency
Ionisation is?
We’re the electrons of an atom gain enough energy to leave it.
How do electrons move between the different energy levels of an atom?
Electrons with the lowest energy will be in the energy shell closest to the nucleus, however by gaining energy they can move to higher shells.
What is an absorption spectra?
Electrons absorb a particular frequency of radiation to get to a higher energy level.
You can see this if a continuous spectrum of visible light shines through a gas-the electrons in the gas atoms absorb certain frequencies of the light,making gaps in the otherwise continuous spectra, these gaps appear as dark lines.
What is an emission spectra?
Electrons are unstable in the higher energy levels so they tend to fall form higher to lower levels, losing energy by emitting radiation of a particular frequency , this gives a series of bright lines.
Explain how astronomers use spectra to work out what stars are made of.
Energy levels in atoms or different for each element- so each element has its own line spectrum. The photosphere of a star emits a continuous spectrum of radiation, this radiation passes though the gases in the stars atmosphere,which produces emission and absorption lines in the spectrum.
By looking at the position of these lines in the star’s spectrum, you can work out what chemical elements are present in the star’s atmosphere, by comparing it with known spectra in the lab.
