Issued Wed, Jan 17 Due Wed, Jan 24

Required reading for this week: F+T 1.1-3, 1.6 (Optional: Beiser, Ch. 2)

Please show your work on all problems. The answers to many F+T problems are in the back, so NO credit will be given to answers with hard to follow (or missing) work. Organize your homework so that the grader can follow your solution clearly. Explain (in words) what you are doing, and what assumptions you make, when it seems appropriate.

1 a) F+T 1.1

b) F+T 1.2b (part b only) Note: This is just an order of magnitude problem! Please state your assumptions clearly.

c) The "Bohr radius" of hydrogen is given in F+T as

[*] Use the techniques discussed in class to find the Bohr radius, . (in Angstroms, meters, or cm, as you wish)

2. F+T 1.8

3. F+T 1.9

4. The photoelectric effect: Given that the threshold wavelength of light required to eject electrons from the surface of platinum is 2000. Å:

a) Calculate the work function of platinum. (Give your answer in eV.)

b) If you shine ultraviolet light (wavelength 1600. Å) on silver, what is the maximum kinetic energy of photoelectrons emitted?

c) What happens if you shine light with wavelength 2500 Å on platinum?

5. Imagine doing a photoelectric experiment. You illuminate a metal with light of wavelength 200 nm and you observe that the maximum voltage you can apply (before you don't see any more photoelectric current) is 4.0 Volts. Then, you illuminate the same metal with light of wavelength 450 nm, and the maximum voltage is now 0.7 Volts. From this data, find Planck's constant, h, and the work function of the surface. (Give h in units of eV s. Give the work function in units of eV. Be sure you do NOT use the known value of h anywhere in your calculations!)

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