Question

How did the photoelectric effect change the world?

Answer 1

It introduced us to quantization in an experimental way!!!

Explanation:

The Photoelectric Effect led us to reconsider the wave-like nature of light!

The incredible thing about the photoelectric effect is that when you shine light onto a metal surface and you have emission of electrons the number of them is dependent upon the INTENSITY of the light while the KINETIC ENERGY (how fast they fly away) depends only upon the FREQUENCY of the light you use!!!!!!

This fact tells us that light comes in packets (particle like) each of quantized energy proportional to frequency: so if you have a certain light, say green, it will be made of packets of energy each of the same amount in the form of `E=hf` where `h` is a constant and `f` the specific frequency of green light.

So, the metal when you increase the intensity simply receives more packets (all of the same energy `E=hf`) while if you increase the frequency it receives more energetic packets (making the electrons fly away with higher Kinetic Energy)!!!!

Hope it is not confusing!