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From the scattering of sunlight, J. J. Thomson calculated the classical radius of the electron as having the value $2.82 \times 10^{-15} \mathrm{m} .$ Sunlight with an intensity of $5.00 \times 10^{2} \mathrm{W} /$ $\mathrm{m}^{2}$ falls on a disk with this radius. Assume light is a classical wave and the light striking the disk is completely absorbed. (a) Calculate the time interval required to accumulate 1.00 $\mathrm{eV}$ of energy. (b) Explain how your result for part (a) compares with the observation that photoelectrons are emitted promptly (within $10^{-9} \mathrm{s} )$

a. 148 \text { days }

b. \text { see explanation }

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{'transcript': "in this exercise we have, the classical rate is of the electric given by 2.82 times 10 to the minus 15 meters. And we have some light, often intensity, ah, 500 watts per square meters, the chimes upon a disk that has the same radius as the classical radius of the election and in question A. We have to calculate what's the time belt A t for the disk to absorb an energy off one election vote? Yeah, So the first thing we need to notice is that one electron vote is the same as 1.6 times 10 to the minus 19 Jews and that the energy is able to the power times that the teeth and the power is just the intensity of the lights times the area, this case, the area of the disc times at the T. So this is gonna be I times the area of this, which is pie Our square that times of the tea. So no, the tea is e over. I high r squared. In our case, E is 1.6 times 10 to the minus 19 jewels. I iz 500 watts for square meters, part times pi times The radius, which is 2.82 times 10 to the minus 15 which results in a time of 1.8 28 times 10 to the seventh seconds. Okay, and this is the predicted time. Lag off the four electric effect, given the light off 500 watts per square meters and in question, be Ah, it's asked why this doesn't happen in the quantum mechanics. And what that what does it tell about quantum mechanics about the four electric effect? Well, it doesn't happen in quantum mechanics because the four electric effect the quantum for electric effect doesn't depend on the intensity I. So for electric, full electric effect does not the panel intensity, but on energy off single Fulton's, which I'm gonna call IGA, do you? And for that reason, the photoelectric effect is purely quantum. So for electrical fact, P E is purely quantum and classical mechanics fails completely when trying to to describe the four electric effect"}

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