Variables
What is the minimum frequency needed to emit electrons from a metal?
Threshold frequency
What does the slope of the KE vs frequency graph represent?
Planck’s constant (h)
Which theory predicted that increasing light intensity increases electron energy?
Classical wave theory
What happens if light intensity increases but frequency is constant and above threshold?
More electrons are emitted, but kinetic energy stays the same
What does the x-intercept of the KE vs frequency graph represent?
Threshold frequency (f₀)
Why did classical wave theory fail to explain the photoelectric effect?
Could not explain threshold frequency, instantaneous emission, or energy depending on frequency
Which three variables are key in the photoelectric effect?
Frequency, intensity, threshold frequency
How does the graph shift if a metal with a higher work function is used?
X-intercept moves to higher frequency; slope stays the same
How does Einstein’s photon theory explain the observations?
Light comes in photons; energy per photon = hf; electrons emitted if hf ≥ work function; explains KE and threshold frequency