Lesson 12: 3.12 Photoelectric Effect
Duration of Days: 1
Lesson Objective
Explain the quantitative relationship between the photon energy absorbed by an atom or molecule and the velocity or kinetic energy of an ejected electron.
How does light behave as a particle (photon) during interactions with atomic matter?
What is the threshold frequency required to eject an electron from a metal surface?
Photon
Photoelectric Effect
Work Function
Threshold Frequency
Planck's Constant
Wavelength
Learning Objective 3.12.A; Suggested Skill 5.F (Mathematical Routines - Calculate with constants)
Connects to light particle duality using E = hv and c = lambda v. Students calculate the energy of incoming photons and apply the law of conservation of energy to determine the velocity or kinetic energy of ejected electrons (Ephoton = work function + KE electron).
Support: Provide an explicit algebraic constants reference bank on handouts showing h (Planck’s constant) and c (speed of light) along with their baseline metrics.
Extension: Have students solve a multi-step problem where they are given the wavelength of light hitting a metal and must calculate the maximum kinetic energy of the escaping photoelectrons in Joules.
A laser emits light with a wavelength of 4.50x10^-7 m.
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Calculate the frequency of this light wave.
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Calculate the energy, in Joules, of a single photon emitted by this laser.