Question A.1 (1 points) What is the cutoff wavelength cutoff for sodium and what is your uncertainty in this wavelength? Provide the following two explanations: • Explain what you are looking for in order to make this determination. • Explain why it is easiest to make this measurement with maximum intensity Question A.2 (1 point) The relationship between wavelength, speed and frequency for a traveling light wave is c = \f. Use this to report a determination of the cutoff frequency fcutoff with uncertainty for sodium
A.1 541 nm. I see this as the longest wavelength the CAN NOT liberate electrons. I am only able to affect changes by about 3 nm to the wavelength so I will claim this as my uncertainty. So, for sodium as the target, the cutoff wavelength is (541 + 3)nm It was easiest to measure with maximum intensity because this means the number of photons per time was high so it was quicker to see whether a certain wavelength would be able to liberate electrons. One photon can liberate one electron A.2 Let's use a value for the speed of light from the internet that has a few extra digits of precision (use five here) compared to the wavelength (above value has three significant figures): c = 2.9979. 108 m/s. Scutot = c/Acutoff so of = 8($) = 81. fcutoff = (554 + 3) - 102 Hz where I only kept one significant figure in the uncertainty. .
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