Photons and the Photoelectric effect

In summary, the conversation discusses the calculation of wavelength of light incident on the surface of metallic sodium, given the work function and maximum speed of emitted photoelectrons. The relationship between frequency and wavelength of light is also mentioned, along with the formula for calculating kinetic energy. By dividing the sum of kinetic energy and work function by Planck's Constant and dividing the speed of light by frequency, the wavelength of the light can be determined.
  • #1
MrDMD83
25
0

Homework Statement



Light is incident on the surface of metallic sodium, whose work function is 2.3 eV. The maximum speed of the photoelectrons emitted by the surface is 1.08 106 m/s. What is the wavelength of the light?



Homework Equations



e=hf

p=h/wavelength


The Attempt at a Solution



None so far
 
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  • #2
What is the kinetic energy imparted to the electron and thus what was the total energy of the photon.
 
  • #3
Could you be a bit more specific?
 
  • #4
Well you know the photon energy is the energy needed to remove the electron plus the kinetic energy of the emited electron. You are given the work function (i.e. the energy required to remove the electron) and the electron speed from which you can work out the kinetic energy of the electron. You have already stated the relation between photon energy and frequency. What is the relationship between frequency and wavelength of light?
 
  • #5
So I use .5mv^2 to get the KE.
From there I divide the sum of the KE and work function by Planck's Constant. I then divide c by f to get the wavelength?
 
  • #6
Ok, I got it. I made the problem more difficult than it needed to be. Thank you for the help.
 

FAQ: Photons and the Photoelectric effect

1. What is a photon?

A photon is the smallest unit of light or electromagnetic radiation. It is considered both a particle and a wave, and carries energy and momentum.

2. How does the photoelectric effect work?

The photoelectric effect is the phenomenon where electrons are emitted from a metal surface when it is exposed to light. When a photon of sufficient energy collides with an electron in the metal, it can transfer its energy to the electron, causing it to be ejected from the metal.

3. What is the relationship between photon energy and frequency?

According to the equation E=hf, where E is energy, h is Planck's constant, and f is frequency, the energy of a photon is directly proportional to its frequency. This means that higher frequency photons have more energy than lower frequency photons.

4. Can the photoelectric effect be explained by classical physics?

No, the photoelectric effect cannot be explained by classical physics. Classical physics suggests that increasing the intensity of light should increase the number of electrons emitted, but in reality, the frequency of light is the determining factor for the energy of the emitted electrons.

5. How is the photoelectric effect used in technology?

The photoelectric effect is used in various technologies such as solar panels, photodiodes, and photomultiplier tubes. These devices utilize the conversion of light energy into electrical energy to power devices and detect light. The photoelectric effect also plays a crucial role in photography and image sensors in digital cameras.

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