[Music] hi and welcome back to three signs lesson coal UK by the end of this video you should be able to calculate the charge flow in a circuit this is a relatively straightforward topic but it is important that you learn it and the last couple of videos will be looking at the electric current and series and parallel circuits so in this video we're going to take a closer look at what meant by electric current and then use this to calculate the charge flowing in a circuit so we're going to start by looking at electrical charge electrical charge is measured in coulombs and I have the symbol capital C a current of 1 ampere means that we've got 1 Coulomb of charge flowing per second so in other words the size of the electric current is the rate of flow of electrical charge now we can use this to work out the charge flow in a circuit to calculate that we use this equation the charge flow in coulombs equals the current and amp ere's multiplied by the time in seconds now you will not be given this equation in the exam so you'll need to learn give the question for you to try calculate the charge flowing in this circuit in 20 seconds pause the video and try this yourself okay so here's the equation the charge flow equals the current multiplied by the time so the current of no point three amperes and the time is 20 seconds put a live into the equation gives us a total charge flow of six coulombs here's another question for you 360 coulombs of charge flows around the circuit and 400 seconds calculate the current in the circuit now to answer this question you'll need to rearrange the equation to calculate the current suppose the video now and try this yourself okay so here's the equation again the chart flow equals the current multiplied by the time we need to rearrange this to calculate the current so here's the rearranged equation the current equals the charge flow divided by the time in this case the charge flow is 360 coulombs and the time is 400 seconds putting these into the equation gives us a current of Northpoint 9 amp ere's remember that you'll find plenty more questions on calculating charge flow in my vision workbook and you can get up I click on the link above okay so hopefully now you should be able to calculate the charge flow in the circuit [Music]