| describe the big bang theory | the big bang theory model states that all the matter that exists was at one time compressed into a single point
around 13. 8 billion years ago, the big bang distributed all the matter evenly in all directions, the the matter started to clump together, attracted by gravity, to form the stars and galaxies that we see today.
The expansion generated by the big bang was great enough to overcome gravity |
| what evidence do we have for the big bang theory? | the big bang theory predicts that as the universe expanded, it cooled. Cosmic microwave background radiation has been detected in space as evidence of this cooling.
observation of distant stars show what is called a red shift in their colour spectrum. This red shift in galaxies is evidence that galaxies are moving away from us, indicating that they are moving away from a single point where the big bang occurred |
| how old is the earth estimated to be | around 13.8 billion years old |
| What is a light year | the distance that light travels in one year
measured in metres |
| what is the speed of light in a vacuum | 3x10^8ms-1 |
| how can you calculate distance when given number of light years and time taken | distance = speed x time
where speed is the speed of light
time is the time taken in seconds |
| what is white light made up of | a range of colours red orange yellow green blue indigo violet these colours can be separated by splitting white light with a glass prism to obtain a spectrum |
| what is the relationship between frequency of a visible light wave and how much it is refracted by | higher frequency colours of light are refracted more than lower frequency colours of light
violet is refracted the most and red light the least |
| what is a spectroscope used for | a spectroscope uses a prism to display the colours that make up a source of light |
| using a spectroscope, from what kind of light could we obtain a continous spectrum? | a source of white light |
| how could we identify the elements present in stars from its line spectrum | each element in the periodic tale produces a unique line spectrum when heated, consisting of specific colours at specific wavelengths seen as their bands
by analysing the line spectrum that came from sources of light like stars, we can determine the chemical elements that make up that star |
| what is a telescope | device used to observe the universe |
| what are optical telescopes used for | used to observe visible light from space
small ones allow amateurs to view the night sky relatively cheaply, but large ones are for for professional astronomers to use |
| name some disadvantages of optical telescopes | they can only be sued at night
they cannot be used if the weather is poor or cloudy |
| what are radio telescopes used for | detail radio waves coming from space |
| what are the advantages and disadvantages of radio telescopes compared to optical telescopes | they are large and expensive
but they can be used in bad weather because radio waves are not blocked by the clouds, as they pass through the atmosphere
they can also be used in daytime or at night |
| what are x ray telescopes used to | observe the x ray region of the electromagnetic spectrum |
| name disadvantages of x ray telescopes | x rays are blocked by the earths atmosphere so x ray telescopes need to be at high altitude, flown in balloons or carried in satellites above the earths atmosphere |
| what are space telescopes used for | to detect objects in the universe that emit electromagnetic radiation such as infrared x-rays and gamma rays which are blocked by the earths atmosphere |
| what are the advantages and disadvantages of space telescopes | they are difficult and expensive to launch and maintain
if anything goes wrong, sometimes only astronauts can repair them
however they can observe the whole sky and operate at night and day time |
