Download Photoelectric Effect - Data Analysis Exercise

The Photoelectric Effect Demonstration
http://phet.colorado.ed.au/en/simulation/photoelectric
First, with the circuit set up so that the battery is attracting electrons:
1. The photoelectric effect occurs when ______________ shines on a metal. Electrons can absorb the
energy from the light. If there is enough energy, they can __________ ___________ from the
metal and become free electrons. They are now called ______________
The photoelectric effect was first observed in 1887 by Heinrich Hertz.
2. Draw a rough outline of the circuit.
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3.
When electrons are ejected from the surface of the metal, they all make it across the gap to the other
side because the other terminal is ___________ ,and the electrons are _____________ to it.
4.
With the light set on ultraviolet ( = 360 nm), what is the effect of changing the intensity
(brightness)?
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5.
With the light set on red light ( = 70 nm), what is the effect of changing the intensity?
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6.
What effect does changing the frequency/wavelength have?
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7.
For sodium, what is the threshold wavelength and threshold frequency?
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8.
For zinc, what is the threshold wavelength and threshold frequency?
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9.
Below the threshold frequency, _____________ electrons are ejected, no matter how intense
(bright) the light source is.
Above the threshold frequency, electrons are _____________ ejected, no matter how dim the light
source is.
Next, with the circuit set up so that the battery is repelling electrons:
1. Draw a rough outline of the circuit.
Include space here
2.
When electrons are ejected from the surface of the metal, they ________ _________ all make it
across the gap to the other side. This is because the anode is __________, so it ____________ the
electrons. Only the electrons with the most energy (the fastest electrons) can make it across.
3.
For sodium, with the wavelength on 400 nm, what is the stopping potential?
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4.
The stopping potential (stopping voltage) is the ____________ voltage needed to stop ALL of the
electrons from getting across.
5.
The stopping potential gives us an indication of the maximum ___________ ____________of the
electrons.
6.
For sodium, with the wavelength on 360 nm (ultraviolet), what is the stopping potential? What is
the maximum kinetic energy of the photoelectrons?
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7.
Does the intensity affect the stopping potential? So, does the intensity affect the maximum kinetic
energy of the electrons?
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8.
What effect does changing the intensity of the light have on the experiment?
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9.
What effect does changing the frequency of the light have on the experiment?
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Problems with the Wave Model of light!!!
The wave model of light predicts that the energy of a light wave is found from its ______________
So the kinetic energy of the electrons should be affected by the __________ of the light. The wave
model also predicts that the frequency of the light should have ________ ____________on the energy.
But this is not observed! So something is wrong with the wave model!
To overcome these problems, Albert Einstein suggested that light comes in tiny packets or particles
called __________ , and the energy of these photons is given by: ____________