Find Potential Difference from Frequency & KE

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SUMMARY

The discussion focuses on calculating the potential difference from the frequency of incident light and the kinetic energy of emitted electrons using the equations E = hf - W and V = W/q. Given a frequency of 7.4 x 1015 Hz and a kinetic energy of 1.9 eV, the calculated stopping potential is 1.9 V, which does not match the expected answer of 2.7 V. The discrepancy arises from the need to correctly calculate the work function W using the energy E derived from the frequency and Planck's constant.

PREREQUISITES
  • Understanding of the photoelectric effect and related equations
  • Familiarity with Planck's constant (h = 6.626 x 10-34 J·s)
  • Knowledge of electron charge (e = 1.602 x 10-19 C)
  • Ability to convert between electron volts and joules
NEXT STEPS
  • Calculate the work function W using the equation W = hf - KE
  • Learn about the photoelectric effect and its implications in modern physics
  • Explore the concept of stopping potential in photoelectric experiments
  • Review energy conversion between electron volts and joules for accurate calculations
USEFUL FOR

Students studying quantum physics, educators teaching the photoelectric effect, and anyone interested in the principles of electron emission and energy conversion in light-matter interactions.

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Homework Statement



How would we find the potential difference given the frequency of the incident light and the kenetic energy of an the emitted electrons?

Homework Equations



E= hf-W
V= w/q
e= 1.602*10^-19

The Attempt at a Solution



Given: f= 7.4*10^15 Hz
KE= 1.9eV
Required: potential difference

Solution: KE= 1.9eV * 1.602*10^ -19 J/eV = 3.0438*10^-19

V= 3.0438*10^-19/ 1.602*10^ -19 = 1.9

The answer is supossedd to be 2.7, I don't think I'm doing this the correct way.
 
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The stopping potential would be 1.9V, not sure what p.d. they are asking for though.
 
Use the 1st equation you wrote,

E = hf - W

To get W, you need to calculate E and hf.
 
Even when you do that, you wouldn't get 2.7..
 

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