so quantum physics at a level what's it really about well i suppose it really builds up on the work that you might have already done on the chapters on waves or looking at maybe some of the particle physics and basically we think about particles perhaps we've got these electrons here which i'm representing with these bits of lego the particle model maybe explains what's happening in a lot of chemistry it explains what's happening if we think about electrons going around a circuit but that's a model for explaining the world around us just like we can use the wave model to perhaps explain the behavior of light when it does things like refraction and reflection and so on now these are both models that we can use in physics but sometimes they don't quite explain everything that we actually observe around us and one example of this is something called the photoelectric effect and this is really to do with the surface of materials including metal so perhaps we had an electron on the surface of that material if we were to look at shining light on it sometimes if you energize that surface by shining light on it or other sorts of electromagnetic radiation we can get the electrons to leave so effectively you've got light coming in that energizes the surface the electrons gain energy and then they can escape now the thing is the wave model of light doesn't explain how electrons can leave or not leave at certain frequencies and really what we can say is that although we often think about light as a wave light can also be thought of as a small bundle of energy a packet of energy and therefore a particle and here i've got what we call photons now the energy of a photon of light is equal or it's proportional to the frequency so when you've got something which is a higher frequency perhaps we have some blue light over here these blue photons have a higher frequency and a corresponding higher energy and we say that e is equal to hf where h is just a constant so effectively the higher the frequency of that electromagnetic radiation the higher the energy and you might have seen that at gcse if you've got things like x-rays or gamma rays they are more energetic and that means they're more ionizing than things like microwaves and radio waves and basically the photoelectric effect can only be explained with the particle-like nature of light where effectively one photon interacts with one electron okay in actual fact the energy of that photon um it has to overcome something called the work function of that material so that's as the electron maybe leaves the surface and then any extra energy it has is then the kinetic energy of that photoelectron as it moves away but that will all be explained as you go into a level something else um that we actually look at and this is something you might have seen is electron energy levels and this is really inside the atom so not just material on the surface but this could happen inside and effectively electrons can exist at different energy levels with inside the atom and what they can do is they can move up an energy level uh if it absorbs some energy and when it drops back down it emits a photon now if it does a big drop perhaps from here to here it's going to give out a lot of energy and because e is equal to hf that means that maybe this photon it gives out is perhaps a green photon maybe when it goes through a different energy change and maybe drops from this level to this level it gives out a different amount of energy and therefore a different frequency and depending on the size of the energy gap it gives out different colored or different frequency photons now if you were to look at that you maybe energize something perhaps you heat it up perhaps it's um with an electric field what we then see is something called an emission spectra okay so maybe when you have this particular type of element it only gives out light in these colors okay now you might have seen again something similar at gcse especially if you're looking at space and the red shift of starlight because what we often then have is an absorption spectra and you can see it this is basically um the different colors or yeah the different colors of light which are absorbed by um that element okay so effectively these are the photons that this can absorb because the electron can only go between certain energy levels so that's an absorption spectra and this is an emission spectra and when we look at starlight we look at how the spectral lines are shifted often towards the red end as that thing is moving away from us we have something called wave particle duality and basically what this means is that the wave model on its own isn't enough and the particle model on its own isn't enough and we actually combine the two to actually think about how things behave in real life so sometimes things appear to behave as a wave if we're thinking about light it can refract it can diffract and that's wave-like behavior but light also behaves like a particle which explains a photoelectric effect conversely electrons which we often think about as these small particles they also have wave-like behavior and in actual fact the wavelength is equal to h the constant that we had over here over the momentum of that particle so even things that we consider as particles also have like a wave like property as well and in actual fact we can get electrons to diffract okay so we can send electrons they behave as a wave as they're traveling along and this means that they diffract and we can actually see that diffraction pattern in the lab it also explains in a way why we only have distinct certain distinct energy levels where electrons can exist and that's because inside the atom we have a standing wave set up of these electrons as they're orbiting the nucleus and these can only exist in certain or i guess predetermined levels but again it gets a little bit complicated but you will cover this as you go through a level physics so nothing here is anything like you've done at gcse beforehand and also you can take this and you can run with it you can maybe watch other videos on youtube you can do some reading because the quantum world gets really really strange you've got quantum tunneling quantum locking all of these different bits and pieces but in terms of a level this is often taught in the first year after you've been looking at waves and what we tend to look at are the photoelectric effect we've got electron energy levels and we've got this wave particle duality you