ITEM 7: Photovoltaic (PV) panels receive a broad spectrum of light during the daytime. The spectrum includes short wavelength ultraviolet radiation to longer wavelength infrared radiation. Which of the following is a true statement concerning PV panels and solar radiation? a. PV panels respond most favorably to the visible part of the spectrum. b. Shorter wavelength photons will not trigger the photoelectric effect. c. Longer wavelength photons will be absorbed, but cause heating of the panel. d. All of the above are true statements.

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.