2.6 - The universe Flashcards

1
Q

What is used to split light into its different wavelengths?

A

Glass prism or a diffraction grating.

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2
Q

What can line emission spectra identify?

A

Different elements, since the spectra for each element is different and unique.

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3
Q

How did scientists identify the chemical composition of stars?

A

Observe the light they emitted through a spectroscope and compare the line absorption spectra with the spectra of known elements

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4
Q

What is a continuous emission spectrum?

A

A complete spectrum of colours showing all wavelengths of light (a full rainbow)

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5
Q

What is the difference between a line absorption spectra and a continuous absorption spectra?

A

Continuous spectra has all the wavelengths while line spectrum only contains some of the wavelengths.

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6
Q

What is the difference between a continuous emission spectra and a line emission spectra?

A

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.

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7
Q

What is the cosmological red shift?

A

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

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8
Q

Who observed spectra from distant galaxies to demonstrate red shift?

A

Sir Edwin Hubble

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9
Q

What two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?

A

The further away a galaxy is, the faster it is moving.

The further away a galaxy is, the greater the observed increase in wavelength

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10
Q

What does the red-shift provide evidence for?

A

Provides evidence that the universe is expanding

Supports the Big Bang theory

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11
Q

What dose the Big Bang theory suggest?

A

The entire universe started from a very small, hot and dense region in space

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12
Q

Compare the observed red shift of two galaxies, one further away than the other.

A

The galaxy that is further away is travelling faster

The observed red-shift is greater the further away it is

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13
Q

What does CMBR stand for?

A

Cosmic Microwave Background Radiation

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14
Q

What is Cosmic Microwave Background Radiation?

A

Radiation that started as gamma waves but was stretched into longer wavelength microwaves by the Universe expanding

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15
Q

How does the existence of CMBR support the expansion of the universe?

A

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

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