Correct graph of current vs voltage (photoelectric emission)

In summary, the conversation discusses a circuit used for investigating photoelectric emission and asks which graph shows the current variation when the two electrodes are illuminated with uniform monochromatic light. The work function of electrode E is higher than that of electrode F, resulting in a negative stopping potential and a negative current when electrons are released from F and travel to E. The answer to the question is either A or C.
  • #1
songoku
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331

Homework Statement


The diagram shows a circuit used for the investigation of photoelectric emission. The two electrodes E and F are made of different metals. The work function of electrode E is higher than that of electrode F.
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Which of the following graphs show the variation the current (flows from E to F) versus voltage (of E with respect to F) when the two electrodes are illuminated with a uniform monochromatic light? Assume the magnitude of the saturation current for either electrodes is same during this experiment
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Homework Equations


Not sure

The Attempt at a Solution


1. E has higher work function means that the electrons are harder to be released from E but I do not know how work functions affects the question

2. When current = 0, is the voltage = stopping potential?

3. My guess:
The graph starts from negative voltage, means that the voltage of E is lower than F. Photoelectrons will be attracted to F so the electrons will flow from F to E and current from E to F resulting in positive value of current. When the voltage changes (becomes more positive) the current will decrease until zero then flow in opposite direction resulting in negative value of current. The answer is C ?

Thanks
 

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  • #2
songoku said:
My guess:
The graph starts from negative voltage, means that the voltage of E is lower than F. Photoelectrons will be attracted to F so the electrons will flow from F to E and current from E to F resulting in positive value of current. When the voltage changes (becomes more positive) the current will decrease until zero then flow in opposite direction resulting in negative value of current. The answer is C ?
Your argument is reasonable, but only leads to A or C.
To distinguish those, consider zero applied voltage. What will shining a light on the electrodes do to each? How might that relate to the work function?
 
  • #3
haruspex said:
Your argument is reasonable, but only leads to A or C.
I think the value of stopping potential will be negative.

To distinguish those, consider zero applied voltage. What will shining a light on the electrodes do to each? How might that relate to the work function?
At that situation, electron will be easier to be released from F then it will travel to E resulting negative current? So the answer is still C?

Thanks
 
  • #4
songoku said:
I think the value of stopping potential will be negative.At that situation, electron will be easier to be released from F then it will travel to E resulting negative current? So the answer is still C?

Thanks
That seems right to me.
 
  • #5
Thank you very much haruspex
 

Related to Correct graph of current vs voltage (photoelectric emission)

1. What is the relationship between current and voltage in a photoelectric emission graph?

The relationship between current and voltage in a photoelectric emission graph is directly proportional. This means that as the voltage increases, the current also increases.

2. How is the photoelectric emission graph different from a typical current vs. voltage graph?

The photoelectric emission graph differs from a typical current vs. voltage graph in that it shows a sudden increase in current at a certain voltage, known as the threshold voltage. This is due to the emission of electrons from a metal surface when exposed to light.

3. What does the slope of a photoelectric emission graph represent?

The slope of a photoelectric emission graph represents the photoelectric current, which is the number of electrons emitted per second from the metal surface. A steeper slope indicates a higher photoelectric current.

4. How does the intensity of light affect the photoelectric emission graph?

The intensity of light does not affect the photoelectric emission graph. The only factor that affects the graph is the frequency of light, which determines the energy of the photons and therefore the kinetic energy of the emitted electrons.

5. What is the significance of the x-intercept in a photoelectric emission graph?

The x-intercept in a photoelectric emission graph represents the threshold voltage, which is the minimum voltage required to emit electrons from the metal surface. This value is dependent on the material and the frequency of light used.

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