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What is used to split light into its different wavelength
A diffraction grating
What can line emission spectra identify
Different elements, since the spectra for each element is different and unique
How did scientist identify the chemical composition of stars
They observe the light it emitted through a spectroscope then compare the line absorption spectra with the spectra of known element
What is red-shift
Observation of increase in the wavelength of light caused by the source moving away from the observer
Who observed spectra from distant galaxies to demonstrate red shift
Sir Edwin Hubble
What two thing can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?
The further the galaxy are, the faster it is moving and the greater the observed increase in wavelength there are.
What does red-shift provide evidence for?
The universe is expanding
Big bang theory
What does Big Bang theory suggest
The entire universe started from a very small, hot and dense region in space
Compare the observation red-shift of two galaxy, one is further away from the other
The galaxy that is further away travels faster and have greater red shift
What did scientist observe to provide evidence that the universe is expanding at an ever fast rate
The observed supernova, which suggested that the galaxy are moving away at an ever faster rate
Prior to observation of supernova, what was believe about the rate of expansion of the universe and why
The rate of expansion was expected to occur at an ever slower rate.
It was thought that the gravitational forces would cause the rate of expansion to slow down
What does CMBR stand for
Cosmic Microwave Background Radiation
What does CMBR provide further evidence for
The Big Bang theory
CMBR comes from the radiation produced in the Big Bang
How does the existence of CMBR support the expansion of the universe
It is thought that gamma radiation was released in the Big Bang, the expansion of the universe has stretched this radiation, resulting in the microwave radiation present today
How can atomic spectra can be used to identify elements in stars
A star emits a continuous spectrum of electromagnetic radiation. This radiation passes through the gases in the star’s atmosphere.
The atom in the gas absorbs specific wavelength of light. These are shown by a gap in the continuous spectrum. Each gap is called an absorption line and the spectrum is an absorption line spectrum.
Each different elements absorb different wavelength of radiation, depending on its atomic structure. So each element has its own unique absorption lines.
By looking at the position of the line in the star’s spectrum, you can work out what chemical are present in the star’s atmosphere.
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