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Homework #4
•Q1 At what wavelength does the spectrum of a 10000 K type A star peak?
Use Wien’s Law: λ = 3000000 nm/T, so 300 nm. •Q2 Fusion of very light elements to make heavier ones releases energy, as does fission of very heavy elements to make lighter ones. The most "energetically favorable" and stable element from which neither fission nor fusion can release energy is IRON
•Q3 Sunspot brightness, use E = σT4 
•(T1/T2)4 = (5800/4200)4 = 3.6 times brighter