[Music] hi and welcome back to frees science lessons. co.uk by the end of this video you should be able to calculate the total energy transferred by components now this is a relatively straightforward Topic in the last video we saw how to calculate the total charge flowing in a circuit such as this one this circuit has a current of .3 amp and we has to calculate the total charge flowing in 10 seconds now to do that we use this equation the charge in kums equals the current in ampir multiplied by the time in seconds so we've got a current of 0.3 amp and a time of 10 seconds multiplying 0.3 by 10 gives a total charge of 3 kums now whenever charge flows in a circuit work is done in other words energy is transferred we can calculate the energy transferred using this equation the energy transferred in Jews equals the charge flow in kums multiplied by the potential difference in volts and here's a triangle if you prefer to use this now you're not given this equation in the exam so you do need to learn it so here's a question for you to try four kums of charge flows in the circuit calculate the total energy transferred pause the video now and try this yourself okay so to calculate the energy transferred we multiply the charge flow by the potential difference the charge flow is 4 kums and the potential difference is 15 volts putting these numbers into the equation gives us an energy transfer of 60 jewles and that's our final answer here's another question for you three kums of charge flows in the circuit calculate the energy transferred in resistor a now to answer this question first you're going to have to to work at the potential difference across resistor a so pause the video now and try this yourself okay we've got a cell with a potential difference of 30 volts and we've got two resistors in series remember that potential difference is shared across components in series resistor B has a potential difference of 25 volts so resistor a must have a potential difference of 5 volts we know that three Coons of charge flows through the circuit to calculate the energy transferred by resistor a we need to multiply the charge flow by the potential difference 3 multiplied five gives us an energy transferred of 15 Jew and that's our final answer remember you'll find plenty more questions on calculating energy transferred by components in my vision workbook and you can get that by clicking on the link above okay so hopefully now you should be able to calculate the total energy transferred by components [Music]