when you think of light do you think of light as a particle or as a wave it turns out that light can behave both as a wave and as a particle thus we have the expression wave particle duality so light can behave as a wave perhaps you heard of the term electromagnetic waves light is a type of electromagnetic wave it has oscillating electric and magnetic fields so thus is called an electromagnetic waves now these oscillating electric and magnetic fields they are at right angles to each other like any wave light has amplitude it also has a wavelength and it has frequency for instance red light has a wavelength somewhere between 620 and 700 nanometers blue light has a wavelength somewhere between 450 and 500 nanometers so the color of light varies with its wavelength and its frequency another proof that light can behave as a wave has to do with the diffraction patterns that it can form for instance let's say if you have two slits or two opponents and a screen at the back if you were to shine a source of light to the left of those two slits what's going to happen is you're going to get a diffraction pattern as these plane waves as they interact with this opening and they will diffract now as these waves bend around the opening they're going to create an interference pattern on a screen and so what's going to happen is you're going to get areas where it's bright and you're going to get areas where it starts so let me draw a few of these patterns here so this part is going to be a bright spot it's going to appear light above and below it you're going to have a dark spot and then above that you're going to have a bright spot same is true over here you might be wondering why are we getting these alternating bright and dark spots and the answer to that is interference the bright spots represents constructive interference and constructive interference occurs when the wave or the two interferon waves they're in phase of each other and so they reinforce each other the amplitude is doubled the dark spots they represent destructive interference that's when two waves they cancel each other out they're out of phase and only waves can show this Behavior and because light can produce these constructive and destructive interference patterns it's proof that light can act as a wave the light can also behave as a particle and this has been seen in the photoelectric effect so let's say you have a piece of metal and you shine blue light on it blue light has enough energy to eject electrons off of certain metals now the ability of a photon to eject an electron depends on a frequency red light doesn't have enough energy or its frequency is not high enough to eject electrons from certain Metals but blue light can but the fact that light can knock off electrons from a metal it shows that light can behave as a particle because it can knock off another particle from a metal so thus we have this idea of wave particle duality this is where light has a dual nature it could behave like a particle particles of light are known as photons and these photons can behave like waves they could form a diffraction pattern around two openings now electrons behave the same way electrons like photons are very tiny particles subatomic particles the difference between an electron and a photon is that an electron is a charged particle whereas a photon is neutral but like photons electrons have a dual nature they can behave like particles and they can behave like waves if you were to basically blast a string of electrons around two openings it can form an interference pattern much like what we see here on the screen so because electrons like photons can form that same constructive destructive interference pattern of alternating light and dark spots electrons therefore are proven to behave as waves so both electrons and photons have this wave particle duality in some instances they can behave as particles and in other situations they could behave as waves