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iym185
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alrighty, run into another problem in this assignment, while my last question i somewhat get... I am not sure at all what to do here, mainly cause i don't really get the graph...
1. In a photoelectric experiment, the metal plate of an evacuated phototube is illuminated with monochromatic light of wavelength 365 nm. The current I in the circuit, is measured for various values of V, the applied potential difference between metal plate and collector. The results are shown in the below graph.
[PLAIN]http://img263.imageshack.us/img263/2575/graphm.png (i) Calculate the maximum kinetic energy of the photoelectrons.
(ii) Deduce the work function of the metal plate.
Emax = hf - wo
Emax = 1/2mev^2
(i) my friend suggested i use the equation:
E = hc/λ to find the energy... but I am not too sure that's correct.. i mean, we know the λ = 35nm so i can use that to find E, as h and c are also know and such, which would give us:
E = (6.626×10^−34)(3=10^8) / 365x10^-9
E = 5.4x10^-19
im just not sure if that's correct as the equation that i know of for finding the max K.E is:
E = 1/2mv^2
as for part (ii), i know what work function here is:
Work function is the minimum energy needed to remove an electron from a solid to a point immediately outside the solid surface.
and i know the equation to use:
Emax = hf - wo, rearranging to get:
wo = hf - E, the E we can get from above part, h is = 6.626×10^−34, f [i think] can be found using f = c/λ which will give us f = 8.2x10^14
so ya, assuming my part (ii) us correct, I am having trouble with part (i), if anyone could PLEASE help.. ty.
Homework Statement
1. In a photoelectric experiment, the metal plate of an evacuated phototube is illuminated with monochromatic light of wavelength 365 nm. The current I in the circuit, is measured for various values of V, the applied potential difference between metal plate and collector. The results are shown in the below graph.
[PLAIN]http://img263.imageshack.us/img263/2575/graphm.png (i) Calculate the maximum kinetic energy of the photoelectrons.
(ii) Deduce the work function of the metal plate.
Homework Equations
Emax = hf - wo
Emax = 1/2mev^2
The Attempt at a Solution
(i) my friend suggested i use the equation:
E = hc/λ to find the energy... but I am not too sure that's correct.. i mean, we know the λ = 35nm so i can use that to find E, as h and c are also know and such, which would give us:
E = (6.626×10^−34)(3=10^8) / 365x10^-9
E = 5.4x10^-19
im just not sure if that's correct as the equation that i know of for finding the max K.E is:
E = 1/2mv^2
as for part (ii), i know what work function here is:
Work function is the minimum energy needed to remove an electron from a solid to a point immediately outside the solid surface.
and i know the equation to use:
Emax = hf - wo, rearranging to get:
wo = hf - E, the E we can get from above part, h is = 6.626×10^−34, f [i think] can be found using f = c/λ which will give us f = 8.2x10^14
so ya, assuming my part (ii) us correct, I am having trouble with part (i), if anyone could PLEASE help.. ty.
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