1.6 Using Radiation to Investigate Stars

Question 1

Black Body

Answer 1

Is a body or surface which absorbs all the elctromagnetic radiation that falls upon it. Nothing is a better emitter of radiation at any wavelength than a black body at the same temperature

Question 2

Photosphere

Answer 2

Is the layer of gas around a star, that emits light from its several hundred’s of kilometres of depth

Question 3

What is the equation for Wien’s law?

Answer 3

λ_max = W / T
λ_max = the peak wavelength (m)
W = Wien’s constant = 2.90x10^-3 (mk)
T = the surface temperature of the star (K)

Question 4

The inverse square law equation?

Answer 4

I = P / 4πx²
I = intensity (Wm^-2)
P = total power produced by the star (W)
x = distance from the source (m)

Question 5

Stefan’s Law equation?

Answer 5

P = σAT⁴
P = total power produced by the star (W)
A = surface are of the star (m)
σ = Stefan’s constant = 5.67x10^-8 (Wm^-2K^-4)
T = surface temperature of the star (K)