Bright red light pours energy onto a zinc plate: hundreds of joules every minute, hour after hour. The wave model predicts ejection once enough energy has piled up at the electrons. The zinc ejects nothing, all day.
The wave model's prediction is now stated: any frequency should work, given enough intensity or enough time. The first observation of this topic already disagrees. This lesson sets the two side by side.
The wave model predicts that intense low-frequency light should eventually eject electrons, because in the wave model light's energy arrives continuously, spread across the whole surface, and can accumulate over time.
Zinc has a threshold frequency, and red light's frequency lies below it.
So the test is simple: by the wave model, bright red light on zinc should eject electrons after enough time.
The observation says otherwise: bright red light on zinc ejects nothing, no matter how long it shines.
Delivered energy is not what is missing; after a day, the red light has delivered far more energy than a faint ultraviolet flash that does eject electrons.
A model that predicts ejection where none ever happens has something wrong in it.
What is wrong is not yet named; the model has one more test to face first.
Orange light lies below iron's threshold frequency. A powerful orange laser shines on an iron gate overnight. What does the wave model predict, and what is observed?
By the wave model, the orange light's energy accumulates at each electron, so ejection should come eventually.
Orange light sits below iron's threshold frequency.
Below the threshold, no electrons are ejected, however long the light shines.
The wave model predicts ejection by morning; the iron ejects nothing. The prediction fails.
Vasco defends the wave model: 'Perhaps the red lamp on zinc was just too dim. A brighter red lamp would eject electrons.' What does the observation say?
Below the threshold frequency, intensity does not matter.
Bright red light on zinc ejects nothing, no matter how long it shines.
A brighter red lamp delivers more energy each second, and still no electrons leave.
The observation rules Vasco's defense out: no red lamp, at any brightness, ejects electrons from zinc.
Bright red light shines on a zinc plate for a whole day. Red light's frequency is below zinc's threshold. What does the wave model predict, wrongly, about this scene?
Below zinc's threshold, the wave model predicts eventual ejection, and the zinc never ejects. What does this mismatch show?
Zelda says: 'The wave model predicts that even red light should eventually eject electrons from zinc.' Is Zelda correct?
Green light lies below silver's threshold frequency, yet a bright green lamp delivers thousands of joules to a clean silver spoon over an afternoon, and no electrons leave. Which statement says why this observation contradicts the wave model?
Which observation about zinc contradicts the wave model's prediction?
Bright red light shines on zinc all day and ejects nothing. Which part of the wave model's story does this observation break?