Photoelectric Effect and stopping potential

In summary, when 445 nm light strikes a certain metal surface, the stopping potential is 70% of that which results when 410 nm light strikes the same metal. This can be expressed as a ratio of the wavelengths, where the shorter wavelength is 0.7 times the longer wavelength. To identify the metal, the work function must also be considered. With a work function of 2.23 eV and the given ratio of 0.7, the metal is likely potassium.
  • #1
Turion
145
2

Homework Statement



When 445 nm light strikes a certain metal surface, the stopping potential is 70% of that which results when 410 nm light strikes the same metal.

Homework Equations





The Attempt at a Solution



$$P=0.7P'\\ \frac { nE }{ t } =\frac { 0.7nE' }{ t } \\ \frac { hc }{ λ } =\frac { 0.7hc }{ λ' } \\ \frac { λ' }{ λ } =0.7$$
 
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  • #2
And the question is?
Oh and you are neglecting the work function of the metal- I think
 
  • #3
Opps. I didn't realize the question was cut off.

Here's the second part:

Based on this information and the table given in the textbook, identify the metal.

Basically, what is required is to calculate the work function.

A: work function 2.23 eV. Potassium.
 
  • #4
Turion said:
bump

Show your effort please. As suggested, did you take the work function into account? Retry the problem.
 
  • #5


The photoelectric effect is the phenomenon where photons of light strike a metal surface with enough energy to knock electrons from the surface. The stopping potential is the minimum potential difference needed to stop these electrons from reaching the other side of a metal plate.

Based on the given information, we can determine that the stopping potential for 410 nm light is 30% higher than the stopping potential for 445 nm light. This suggests that 410 nm light has a higher energy than 445 nm light, as the stopping potential is directly proportional to the energy of the photons.

Using the equation for the photoelectric effect, we can see that the ratio of the wavelengths of the two lights is 0.7. This means that the energy of 410 nm light is approximately 1.4 times higher than the energy of 445 nm light.

This difference in energy can be attributed to the fact that shorter wavelengths of light have higher frequencies, and therefore higher energies. This is in accordance with the wave-particle duality of light, where it can behave both as a wave and a particle.

In conclusion, the given information about the photoelectric effect and stopping potential provides evidence for the wave-particle duality of light, and highlights the importance of understanding the relationship between wavelength, frequency, and energy in the study of light and its interactions with matter.
 

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 of a certain frequency. This was first discovered by Albert Einstein in 1905 and is an important concept in modern physics.

What is the stopping potential in the photoelectric effect?

The stopping potential is the minimum potential difference that needs to be applied to a metal surface to stop the emission of electrons in the photoelectric effect. It is directly proportional to the frequency of light and can be used to determine the work function of the metal.

How does the intensity of light affect the photoelectric effect?

The intensity of light does not affect the photoelectric effect. It only affects the number of electrons emitted, but not their energy. The energy of the emitted electrons depends only on the frequency of light.

What is the work function in the photoelectric effect?

The work function is the minimum energy required to remove an electron from the surface of a metal. It is different for different metals and can be determined by measuring the stopping potential in the photoelectric effect.

What are the applications of the photoelectric effect?

The photoelectric effect has many applications in modern technology, including solar panels, photodiodes, and photomultiplier tubes. It is also used in spectroscopy and electron microscopy to study the properties of materials.

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