# Physical Chemistry photoelectric question stumped

• jasdell
In summary, a student conducted a photoelectric experiment and found that the kinetic energy of ejected electrons was dependent on wavelength. She was able to determine phi and h using graph plotting.
jasdell

## Homework Statement

a student carried out a photoelectric experiment by shining visible light on a clean piece of cesium metal. She determined the kinetic energy of ejected electrons by applying a retarding voltage such that the current due to the electrons read exactly 0. The condition was reached when eV=(1/2)(m sub e)(velocity)^2 where e is electric charge and V is the retarding potential. Her results are as follows:

wavelength / nm---405-------435.8----480------520-----577.7----650
V / volt-----------1.475------1.268----1.027----0.886---0.667----0.381

rearrange equation to read: frequency= (phi)/(h) + (e/h)V

determine the values of h (planks constant) and phi (work function) graphically.

## Homework Equations

The equation the book rearranged was hv=(phi)+ (1/2)(m sub e)(velocity)^2

In class the following day our teacher gave us the equation that I believe he some how derived from the rearranged equation: 1/wavelength=(c/h)(eV)+ c(phi)/h^2 or h2 my notes were hurried and I can't really tell... not to mention I just don't see how either one could be derived unless I'm missing something (probable)

## The Attempt at a Solution

I've tried playing with it some but I really don't know where to start with this question.

I'm not even positive what it is asking for. I assume its asking me to find plank's constant and the work function from the data given but am I supposed to make a scatter plot of my results or what?

I think I'm just having trouble wrapping my brain around exactly what it wants and trying to find a method of attack.

Any help on this would be extremely useful

jasdell said:

## Homework Statement

a student carried out a photoelectric experiment by shining visible light on a clean piece of cesium metal. She determined the kinetic energy of ejected electrons by applying a retarding voltage such that the current due to the electrons read exactly 0. The condition was reached when eV=(1/2)(m sub e)(velocity)^2 where e is electric charge and V is the retarding potential. Her results are as follows:

wavelength / nm---405-------435.8----480------520-----577.7----650
V / volt-----------1.475------1.268----1.027----0.886---0.667----0.381

rearrange equation to read: frequency= (phi)/(h) + (e/h)V

determine the values of h (planks constant) and phi (work function) graphically.

## Homework Equations

The equation the book rearranged was hv=(phi)+ (1/2)(m sub e)(velocity)^2

In class the following day our teacher gave us the equation that I believe he some how derived from the rearranged equation: 1/wavelength=(c/h)(eV)+ c(phi)/h^2 or h2 my notes were hurried and I can't really tell... not to mention I just don't see how either one could be derived unless I'm missing something (probable)

## The Attempt at a Solution

I've tried playing with it some but I really don't know where to start with this question.

I'm not even positive what it is asking for. I assume its asking me to find plank's constant and the work function from the data given but am I supposed to make a scatter plot of my results or what?

I think I'm just having trouble wrapping my brain around exactly what it wants and trying to find a method of attack.

Any help on this would be extremely useful

You are given, hv=(phi)+ (1/2)(m sub e)(velocity)^2 and you need to find a solution for v.

Divide both sides by h and see where it leads you.

First equation is:
frequency= (phi)/(h) + (e/h)V

so there is a linear relation between V and frequency plus a constant. If you graph them you can obtain an estimate for the slope as well as ordinate at zero.

## 1. What is the photoelectric effect?

The photoelectric effect is a phenomenon in which electrons are emitted from a material when it is exposed to light or other electromagnetic radiation. This effect was first observed by Heinrich Hertz in 1887 and was explained by Albert Einstein in 1905.

## 2. How does the photoelectric effect relate to physical chemistry?

The photoelectric effect is an important concept in physical chemistry as it provides evidence for the particle nature of light and the quantization of energy. It also has applications in fields such as solar energy, photocatalysis, and photochemistry.

## 3. What factors affect the photoelectric effect?

The intensity and wavelength of the incident light, as well as the properties of the material such as its work function and surface conditions, can affect the photoelectric effect. Additionally, the presence of external electric fields can also influence the emission of electrons.

## 4. How does the photoelectric effect support the wave-particle duality of light?

The photoelectric effect provides evidence for the wave-particle duality of light, as it demonstrates that light can behave like a particle (photon) by transferring its energy to electrons and causing them to be emitted from a material. This effect cannot be explained by classical wave theory, but is consistent with the quantum nature of light.

## 5. Why might someone be stumped by a physical chemistry photoelectric question?

Understanding the photoelectric effect requires a solid understanding of both physical chemistry and quantum mechanics, which can be challenging for many students. Additionally, the topic can be further complicated by various experimental factors and scenarios that may be presented in a question.

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