The sun can be treated as a blackbody at 5780 K. Using EES (or other) software, calculate and plot the spectral blackbody emissive power Ebl of the sun versus wavelength in the range of 0.01 µm to 1000 µm. Discuss the results.

Suppose you measure spectrum of a 40W incandescent light bulb which peaks at a wavelength of 576 nm. Using Wein's displacement law, (eq 1 given above) find the temperature of the source. Using the temperature you found in 1, find the surface area of the 40 W light bulb (use equation 2 assuming ɛ =1 and make a reasonable assumption on temperatures for this calculation. Also, use o = 5.67 x 108 W/m²K*). Determine the energies of the following transitions in the hydrogen atom: n = 5 to n= 2, n= 4 to n= 2, n= 3 to n=2 (Hint: Find the change in energy using equation (4)) Find the wavelength (in nm) of each transition you found in question no.3 (Hint: use formula for energy of photon E = hc/h)

Consider a material that is well approximated by a black body. The max. emitted irradiance is found at a wavelength of 445 nm. What is the temperature of the black body. Provide your answer in Kelvin.

Consider two large parallel surfaces. The one on the leftis at T1 = 298 K and has emissivity e =1.0 . The one on theright is at T2 = 77 K and has emissivity e = 0.70 . What is thenet flux of energy from the hotter to the colder surface. (Hint:a surface absorbs a fraction e of the photons incident on it andreflects the rest.)