Quantum Physics: Work Function and Electric Potential

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SUMMARY

The discussion centers on calculating the maximum kinetic energy (K.E.) of photoelectrons emitted from a metal surface illuminated by 200nm wavelength light, with a work function of 3.0 eV and an electric potential of 5V lower than a point of infinity. The maximum K.E. is determined using the equation K.E.max = hf - Φ, where f is the frequency calculated from f = c/λ. The impact of the electric potential on the K.E. of the photoelectrons is also addressed, indicating that the electric potential increases the energy required for electrons to escape the surface.

PREREQUISITES
  • Understanding of the photoelectric effect and work function
  • Familiarity with the equations K.E.max = hf - Φ and f = c/λ
  • Knowledge of energy units, specifically the conversion between electron volts (eV) and joules
  • Basic principles of electric potential and its effect on charged particles
NEXT STEPS
  • Learn about the photoelectric effect and its applications in quantum physics
  • Study the relationship between electric potential and kinetic energy in charged particles
  • Explore advanced calculations involving the photoelectric effect with varying work functions
  • Investigate the implications of wavelength and frequency on electron emission in different materials
USEFUL FOR

Students studying quantum physics, particularly those focusing on the photoelectric effect, as well as educators and researchers interested in the interaction of light with matter.

JohnGaltis
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Homework Statement


Metal Surface is illuminated with 200nm wavelength light. Work Function of this metal is 3.0eV and its electric potential is 5V lower than a point of infinity.

Determine max K.E of photoelectrons, which are just emitted from the work surface.

Homework Equations


K.Emax= hf - Φ
f=c/λ
Not sure what other equations.

The Attempt at a Solution


I found f first by using f=c/λ. This way, I got a value of max K.E. But it's a really high mark question so it got to be more than just subbing in values.

I think I haven't yet include the impact the electric potential would have on the photoelectrons. It would cause the max K.E of photoelectrons to increase, right? Since it would be attracted to the metal surface and would need more energy to escape.

What equation would allow me to find the energy required to escape the surface?
 
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Show your calculations. did you convert eV into joules?
 

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