2.6 - The universe Flashcards
What is used to split light into its different wavelengths?
Glass prism or a diffraction grating.
What can line emission spectra identify?
Different elements, since the spectra for each element is different and unique.
How did scientists identify the chemical composition of stars?
Observe the light they emitted through a spectroscope and compare the line absorption spectra with the spectra of known elements
What is a continuous emission spectrum?
A complete spectrum of colours showing all wavelengths of light (a full rainbow)
What is the difference between a line absorption spectra and a continuous absorption spectra?
Continuous spectra has all the wavelengths while line spectrum only contains some of the wavelengths.
What is the difference between a continuous emission spectra and a line emission spectra?
The continuous type contains many frequencies merging into one another with no gaps, while the line type contains only a few distinct frequencies. Hot objects produce a continuous spectrum, whereas gases can absorb energy then emit it at certain specific wavelengths, forming an emission line spectrum.
What is the cosmological red shift?
The shift of line absorption spectra from galaxies to the red part of the visible spectrum. Caused by the light passing through expanding space, which stretches the wavelengths
Who observed spectra from distant galaxies to demonstrate red shift?
Sir Edwin Hubble
What two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?
The further away a galaxy is, the faster it is moving.
The further away a galaxy is, the greater the observed increase in wavelength
What does the red-shift provide evidence for?
Provides evidence that the universe is expanding
Supports the Big Bang theory
What dose the Big Bang theory suggest?
The entire universe started from a very small, hot and dense region in space
Compare the observed red shift of two galaxies, one further away than the other.
The galaxy that is further away is travelling faster
The observed red-shift is greater the further away it is
What does CMBR stand for?
Cosmic Microwave Background Radiation
What is Cosmic Microwave Background Radiation?
Radiation that started as gamma waves but was stretched into longer wavelength microwaves by the Universe expanding
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
