Review standard candles in Edexcel A-Level Physics through known-luminosity definitions, galaxy-distance methods and inverse-square reasoning.
The astronomer Hertzsprung used parallax to determine the distances to some of the variable stars known as Cepheids.
Cepheids are a type of standard candle.
Describe how standard candles can be used to determine distances to stars.
The intensity (of radiation from the candle) is measured
The luminosity of the standard candle is known
The inverse square law is used to determine the distance
[Accept reference to I=L / 4 d^2 with symbols defined]