[Music] hi and welcome back to freiz lessons. co.uk by the end of this video you should be able to describe how potential difference changes in parallel circuits you should then be able to calculate potential difference in parallel circuits in the last video we saw that potential difference tells us about energy transfers taking place in a circuit the potential difference of one volt means that one Jewel of energy is transferred for each coolum of charge that's moving through the circuit so in this series circuit we can see that the cell has a potential difference of 9 volts in other words the current is carrying 9 Jew of energy per Kum of charge now remember that in series circuits potential difference is split between components so in this video we're going to explore potential difference in parallel circuits I'm showing you a parallel circuit here remember that parallel circuits have branches and some of the current passes through each branch so we're going to look at potential difference in circuits such as this one we can measure the potential difference across the cell using a voltmeter like this in this case the potential difference is 6 volts this tells us that the current is carrying six Jew of energy per Kum of charge we can now measure the potential difference across the branches using a volt meter on the top Branch tells us that the potential difference across the top lump is is 6 Vols and using a volt meter on the bottom Branch tells us that the potential difference across the bottom lamp is also 6 Vols so as you can see potential difference in parallel circuits is not like potential difference in series circuits here's the key fact for components connected in parallel the potential difference across each component is the same so here's a circuit for you and I'd like you to determine the potential difference across the top lamp and the cell pause the video and try this self okay this is a relatively straightforward question as you can see the potential difference across the bottom lamp is 12 volts and in a parallel circuit all of the components connected in parallel have the same potential difference so that means that the potential difference across the top lamp will be 12 volts and the potential difference across the cell will also be 12 volts here's a slightly more complicated example I want you to calculate the potential difference across the bottom lump pause the video and try this yourself okay now in this example we've actually got two lamps in series and here they are these two lamps are in parallel with one other lamp remember that for components and parallel the potential difference across each component is the same so that means that the total potential difference across the bottom Branch must be the same as the branch above now looking at the two voltmeters we can see that the right hand lamp has a potential difference of 7 volt this means that the left hand lamp must have a potential difference of 2 volts in other words if we put a voltmeter across both of the bottom lamps like this the total potential difference would read 9 volts and that's the same as the branch above and it's the same as the cell remember that you'll find plenty more questions on potential difference in parallel circuits in my vision workbook and you can get that by clicking on the link above okay so hopefully now you should be able to describe how potential difference changes in parallel circuits you should then be able to calculate potential difference in parallel circuits [Music]