/sci/ - Science & Math

>>15688678
The photoelectric effect is what you said, but the experiment did something different.
You take a single-frequency, known 'intensity' light source, point it at some alkali metal, and measure the current and maximum kinetic energy of the emitted electrons.
A wave model of light would predict that the max kinetic energy of the electrons would increase as intensity increased, and that the current would increase as frequency increased.
However, in the experiment, as frequency decreases, so does max KE. And as intensity decreases, so does current. The wave model doesn't predict this behaviour.
Furthermore, if you lower the light enough below the 'threshold frequency', no electrons will be emitted, regardless of how intense you make the light. The wave model doesn't predict this; the wave model would predict that no matter how low-frequency the light is, you would still get some electrons being emitted.

The max KE of the electrons can be found by applying a voltage across some electrodes, so that the electrons are attracted backwards towards the metal and adjusting the voltage until the current is touching zero.