Photoelectric Effect

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Color 1: Blue

%Transmission Stopping Potential Approx. Charge Time
100 1.34 4
80 1.3 3.5
60 1.27 4.9
40 1.25 8.2
20

1.26

9.2

 

Color 2: Green

%Transmission Stopping Potential Approx. Charge Time
100 .76 5.2
80 .76 7.2
60 .75 7.5
40 .75 8.8
20

.74

11.5

 

Experiment 1, Part B

Light Color Stopping Potential
Yellow

 .685

Green .795 
Blue 1.378 
Violet 1.89 
Ultraviolet 1.91 

 

Analysis:

1) Passing different amounts through did not have any major effect on the stopping potential and the same is true for its maximum energy. The charging time was increased with less light.

 2) Different colors correlated to different stopping potentials with smaller wavelengths producing higher potentials and maximum energies.

3) A quantum theory because the charging time was increased with less light while the stopping potential remained the same.

The intensity of the light was smaller, meaning that less photons were able to flow through the filter and the stopping potential had to lower to compensate.

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First Order 

Color

Wavelength (nm) Frequency (\times10^{14} Hz) Stopping Potential (volts)
Yellow  576 5.2  .685
Green 545  5.5  .795
Blue 435  6.9  1.378
Violet 411  7.3  1.89
Ultraviolet 366  8.2  1.91

 

Second Order 

Color

Wavelength (nm) Frequency (\times10^{14} Hz) Stopping Potential (volts)
Yellow  576 5.2  .684
Green 545  5.5  .802
Blue 435  6.9  1.361
Violet 411  7.3  1.835
Ultraviolet 366  8.2  1.84

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Discussion Questions:

1) No, the stopping voltage does not depend on the light's frequency, only it's intensity. 

2) Yes, the stopping voltage depends on the intensity of the light. A higher intensity begets a higher stopping voltage which begets a higher maximum energy.

3) Yes, before the photoelectrons are emitted they first need to absorb enough energy.

4) Yes, the frequency of light determines how many particles are hitting.

5) No, there is a minimum intensity that must first be met and outside of that the intensity does not matter.

6) No, the transfers of energy do not rely on each other; they are independent.

7) Both are supported.

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