How do you find threshold frequency? (given wavelength and KE of electrons)

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SUMMARY

The discussion focuses on calculating the threshold frequency for electrons ejected from a silver surface when irradiated with light of 230 nm wavelength, resulting in a kinetic energy of 77.67 kJ/mol. The threshold frequency is determined using the equation \( \nu_0 = \frac{W}{h} \), where \( W \) is the work function and \( h \) is Planck's constant. To find the work function, the kinetic energy of a single electron must be derived from the total kinetic energy provided, and the energy of a photon at 230 nm must also be calculated to establish the relationship between photon energy and work function.

PREREQUISITES
  • Understanding of the photoelectric effect
  • Familiarity with Planck's constant (h = 6.626 x 10-34 J·s)
  • Knowledge of the relationship between wavelength and photon energy
  • Ability to convert energy units (kJ/mol to J/electron)
NEXT STEPS
  • Calculate the energy of a photon using the formula \( E = \frac{hc}{\lambda} \)
  • Convert the kinetic energy from kJ/mol to J/electron
  • Determine the work function using the equation \( W = E_{photon} - KE \)
  • Explore the implications of the photoelectric effect in different materials
USEFUL FOR

Students and professionals in physics, particularly those studying quantum mechanics and the photoelectric effect, as well as anyone involved in materials science and photonics.

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If you are told that a silver surface is irradiated with light having a wavelength of 230 nm that causes electrons to be ejected with 77.67 kJ/mol of kinetic energy, how would you find the threshold frequency?



I know that threshold frequency = W / h. W is the work function and h is Planck's constant.



I seriously don't know where to go from there. Obviously, I would be able to get an answer if I could obtain a value for the work function. However, I don't know what equation would allow me to use the given information (the wavelength and kinetic energy) to find the work function value. If anyone could help me with that, that would be great. Thanks!
 
Physics news on Phys.org
If 1 mole of electrons has 77.67 kJ of kinetic energy, how much kinetic energy does 1 electron have?

Also, what's the energy of a photon of wavelength 230 nm?
 

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