got a couple of questions.... firstly, A blue supergiant star has surface temperature 29kK and has total power output 100000 times that of the Sun. where is the wein peak of this stars balckbody curve? I got lambda=9.99*10^-8m, which i know is right. now, radius of sun is 6.96*108m, find radius of supergiant.. so ratio here should give the supergiant a surface area of A=100000A of sun.. solving for that gives r = 2.11*10^11m... but it tells me its wrong??? secondly, A photoelectric experiment uses 265 nm light and a silver target. Find max kinetic energy of photoelectrons. Kmax=hf-W0 h=6.626*10-34 f=c/lambda=1.13*10^15 W0 for silver = 7.43*10^-19 subbing in gives Kmax = 5.738*10^-21J.... and it also tells me that is wrong??? thirdly, Suppose you want to observe neutron diffraction in a crystal with 0.28 nm spacing between lattice planes. Find the momentum of neutrons having wavelength equal to this spacing. found p=2.4*10^-24 kg*m/s Find the kinetic energy of neutrons having wavelength equal to this spacing. found K=1.7*10^.21 J If these neutrons constituted an ideal gas, what would be the gas temperature? How the heck do i do that :S?? thanksss so much for any help!