Review Wien’s law in Edexcel A-Level Physics through peak-wavelength readings, temperature calculations and black-body graph comparisons.
The Sun is a main sequence star.
The Sun will eventually leave the main sequence and become a red giant star.
luminosity of Sun = 3.83 × 10^26 W
As a red giant star, the radius of the Sun will be about 150 times its current radius. Its luminosity will be about 1600 times its current luminosity.
λ_max is the wavelength at which peak power radiation occurs.
Show that when the Sun is in its red giant stage, λ_max is about 1 × 10^-6 m.
current radius of Sun = 7.0 × 10^8 m
Use L = AσT⁴ and A = 4πr² to find the red giant temperature, then use λ_maxT = 2.898 × 10^-3 m K. T = [1600 × 3.83 × 10^26/(4π(150 × 7.0 × 10^8)^2(5.67 × 10^-8))]^(1/4) = 2972 K. λ_max = 2.898 × 10^-3/2972 = 9.75 × 10^-7 m, about 1 × 10^-6 m.