how that the spectrum of thermal radiation for T=300K peaks at approximately 10 microns.

uestion 1:

(a) Show that the spectrum of thermal radiation for T=300K peaks at approximately 10 microns.

(b) At what frequency v does ?(v) have its maximum?

(c) Support or refute the statement (from S. Weinberg, The First Three Minutes, Bantam Books, New York, 1977) that "the average distance between photons in black-body radiation is toughly equal to the typical photon wavelength."

Question 2:

Show that if the field polarization vector in Eq. is taken to be complex:

?^ = 1/?2(x^ + iy^), then the real part of the right-hand side of (3.4.4) represents a cir cularly polarized field with the same time-averaged intensity as the given linearly polarized field, that is, E E = 1/2 E20. Does this field vector rotate clockwise when viewed by an observer looking into the wave (i.e., looking back toward negative z)? If so, the wave is called right circularly polarized according to the optics convention for polarization.

Question 3:

Take the incident field to be circularly polarized and recalculate dW/dt to show that the result given in Eq. remains unchanged.

Question 4:

Estimate the temperature of a blacktop road on a sunny day. Assume the asphalt is a perfect blackbody.

Question 5:

The CO2 molecule has strong absorption lines in the neighborhood of ? = 10?m. Assuming that the cross sections of CO2 molecules with N2 and O2 molecules are ?(CO2, N2)= 1.20 nm2 and ?(CO2, O2) = 0.95 nm2, estimate the collision broadened line width for CO2 in the atmosphere. (Note: Since the concentration of CO2 is very small compared to N2 and O2 in air, you may assume that only N2-CO2 and O2-CO2 collisions contribute to the line width.) Compare this to the Doppler width.