3D.2 Flashcards

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1
Q

what are photoelectrons

A

they are electrons released from the surface of a metal due to be exposed to electromagnetic radiation

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2
Q

what is the work function

A

the minimum amount of energy needed for an electron at the surface of a metal to leave the metal

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3
Q

amplitude for light means

A

brightness

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4
Q

can any photoelectrons be released from shining a red light and why

A

no, because it is below the threshold frequency

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5
Q

what is the threshold frequency

A

it is the minimum frequency of electromagnetic radiation that can cause the emission of photoelectrons from the surface of a metal

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6
Q

what is the photoelectric effect equation

A

hf = 1/2mv^2(max) + work function

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7
Q

what is the stopping voltage

A

it is the minimum amount of voltage required to reduce the photoelectric current to zero. with illuminated with a particle frequency

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8
Q

how do we test for plank constant using a photoelectric cell

A

in a vacuum place the metal on an anode of a cell with a gap to a cathode, shine a light would known frequency at the anode to get electrons to be released starting a current, then you can vary the pd across the photoelectric cell using a variable cell, keep increasing the voltage until the photoelectric cell becomes positive stops emitting electrons, and starts to attach the electrons back to its self, the voltage that makes the Photoelectric cell positive is called the stopping voltage we can use that value to find the maximum kinetic energy, then we can vary the frequency of light and record the stopping voltage for each frequency then we can plot a graph with the y-axis as 1/2mv^(max) and x-axis and the threshold frequency and the gradient = plank constant and the y-intercept is the work function

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9
Q

at the stopping voltage, the kinetic energy would be at

A

a maximum

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10
Q

what is the formula to find the ax Kinetic energy using stopping voltage

A

1/2mv^2 = e x Vs

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11
Q

compare y= mx + c to the photoelectric effect equation

A

y(1/2mv^2(max) = m(h) x(f) - work function

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