Question

2) You’re a physics professor preparing a photoelectric effect lab for your class. When testing the apparatus to be used, you measure a stopping potential of 0.50 V for a wavelength of 485 nm, and a stopping potential of 1.48 V for a wavelength of 350 nm.

a) Is this a lab you can safely give to your class? (That is, does the value of Planck’s constant obtained from these data agree with the accepted value?)

b) What is the work function of the metal in the phototube?

c) A classmate doing the photoelectric effect lab neglected to place the necessary filters over the detector while taking data, allowing some shorter-wavelength light from the room to enter the photocell while attempting to record the stopping potential for the green (546nm) and yellow (578nm) lines in mercury. Will this result in a value of h that is too small or too large?

Answer 1