What this practice covers
These questions are drawn from past CIE 9702 Physics papers and filtered to astronomy and cosmology. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on astronomy and cosmology, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Confusing luminosity with radiant flux intensity. Luminosity is emitted power and is a property of the star; flux intensity is what arrives at a detector and depends on distance.
- Using d rather than 4πd² in the inverse square law.
- Saying a standard candle is an object of known distance. It is an object of known luminosity, from which the distance is deduced.
- Forgetting to take the square root when finding a distance or a radius from a squared quantity.
- Using Celsius in Wien's law or the Stefan-Boltzmann law.
- Saying that a hotter star peaks at a longer wavelength, or that red stars are the hottest.
- Forgetting the fourth power of T in the Stefan-Boltzmann law, or raising only part of the expression to that power.
- Saying redshift means the galaxy is moving away through space, rather than that space between us is expanding.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Astronomy and cosmology revision notes.