# Question 197e6

Jan 22, 2017

Increasing frequency the electrons emitted will have a higher Kinetic Energy (they will travel faster); increasing the intensity will increase the number of electrons emitted but not their speed.

#### Explanation:

This is the great thing about the Photoelectric Effect and made it one of the fundamental experiments that introduced Quantum Mechanics.
Before this effect light was simply a wave BUT after the Photoelectric Effect we started to think of light as packets or quanta of light (photons) carrying energy that is proportional to frequency!
In the Photoelectric Effect increasing the frequency increases the energy transported by our photon/packet of light so that hitting the metal will give this energy to the emitted electron that will then receive this higher energy and fly away faster.

Increasing the intensity we will simply increase the number of packets but not their individual energy (we do not increase frequency!) so more electrons in the metal will use them to fly away but all with a fixed (or lower) energy.

As an example, imagine to have a group of kids receiving their weekly pay: imagine to have \$100# (This is a photon with high frequency and so high energy) and give it all to one kid only (unfair...I know) he will go away very happy indeed!
Now imagine to divide equally between all the kids...they won't be soooooooooo happy as the one in the first example but all of them will go away a bit happy!