1) If light is shone on an anode, a current will be produced containing electron
ID: 1684022 • Letter: 1
Question
1) If light is shone on an anode, a current will be produced containing electrons with a particular maximum kinetic energy. Placing a potential across the metal such that it opposes the current will slow the electrons. You illuminate a cesium surface with light with wavelength 5230 Å and measure a stopping potential V0 of 0.23 V, and then change the wavelength to 4080 Å and measure a V0 of 0.90 V.a. What is the frequency of the 5230 Å wavelength light source?
b. What is the frequency of the 4080 Å wavelength light source?
c. For the electrons with 0.23V stopping potential, find the maximum kinetic energy the electrons will have when they are ejected from the anode.
d. For the electrons with 0.90V stopping potential, find the maximum kinetic energy the electrons will have when they are ejected from the anode.
e. Find an experimental value of Planck’s constant.
f. What is the work function of the anode?
Explanation / Answer
In order to find frequency we know that the units are s^-1, which is also Hertz (Hz). So to find frequency (f), the equation we use is c/lambda = f where c is the speed of light and is equal to 3x10^8 m/s and lambda is the wavelength of the light. For parts a and b we are given the wavelength, so we can just plug the wavelengths into the equation c/lambda = f. for part a, lambda = 5230 angstroms = 5230 * 10^-10 m for part b, lambda = 4080 angstroms = 4080 * 10^-10 m
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