Back to the full dot-point answer
EnglandPhysicsQuick questions
Thermodynamics, space and oscillations
Quick questions on Astrophysics and cosmology: Wien's and Stefan's laws, redshift and Hubble's law - Edexcel A-Level Physics
5short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is black-body radiation?Show answer
A star behaves like a black body, so its colour reveals its temperature: red stars are cooler, blue-white stars hotter. Stefan's law shows luminosity depends very strongly on temperature (the fourth power) and on size (the radius squared), which is why a hot, large star is overwhelmingly luminous.
What is measuring distance?Show answer
Parallax works only for relatively nearby stars, where the angle is large enough to measure. For galaxies far beyond, astronomers use standard candles: comparing the known luminosity with the observed (much fainter) brightness gives the distance, since brightness falls off as the inverse square of distance.
What is q1?Show answer
State Wien's displacement law in words. [1 mark]
What is q2?Show answer
A galaxy recedes at m per second with per second. Find its distance. [2 marks]
What is q3?Show answer
Explain why parallax cannot be used to measure the distance to very distant galaxies. [2 marks]
Have a question we have not covered?
This dot-point answer is short enough that we have not extracted many short questions yet. Read the full dot-point answer or ask Mo, our study assistant, in the chat for follow ups.