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hey this is homework help with electric 5 first of all let's take a look at pages 623-2626 and Jane do a little reading fill in one column and then there's a couple problems to do so this is where you start on page 623 and here's a good example on page 625 probably this is the key right here to any parallel circuit is you have to realize the voltage across each resistor is the same the full voltage of your power source once you get that down if it becomes a little bit easier to solve these type of problems the equivalent resistance is a little bit more difficult down here you see that you're using reciprocal relationships to find the reciprocal of the equivalent resistance that's a little bit more difficult than series or you just add them up some problems you'll be doing a few of these numbers 15 and 60 4 homework number 15 you should be at the back of the book do you want to look there for some help and there's the rest of the reading okay so hopefully you can fill in the column with some reading stuff let's get to the follow-up problems here give you a little assistance with these start with what would be number 15 on page 626 ohm resistors are connected in parallel and placed across a 30 volt battery what is the equivalent resistance of a parallel circuit but we have three resistors they're all the same 15 ohms now to find equivalent resistance it's 1 / r e q equals 1 / r 1 + 1 / R 2 + 1 / R 3 but there's also a sneaky way to do it when all of the resistors are the same when all the resistors are the same you can find req like taking one in dividing by how many you have so since it's 15 and we have three that's pretty easy to find the equivalent resistance be the current through the entire circuit or once you find req from up above to find the current through the entire circuit you find what goes battery so the other thing that we do know req you found in the last and then the voltage of the battery is 30 volts what is the current through each 15 Ohm resistor that would be I equal be over our where you abusing the full Voltage the battery and the individual resistance of each resistor in this case so see is I could be over our free tree sister since they're all the same you only need to do it the power of the circuit that we look to the battery that's what's powering the circuit and we would use the power equation P equals IV where you know what i is that from the last from B you found the current through the entire Circuit by Ohm's law to the battery and now you find the power for the entire Circuit by using the power equation for the battery now the next one we have three resistors i12060a and 42 find the equivalent resistance in this case you're going to have to use the this equation from above Ferrari to cuz whenever I 1 + 1 / 2 + 1 / R3 you can find common denominators to do this you can do it on your calculator in decimal form and then find the reciprocal of your answer as a bunch of ways to do this but it's definitely not easy Stouffer's what you're going to have to do is find out where is 1 / r e q is equal to 1 / r 1 + 1 / R 2 + 1 / R 3 can you use dessert bars R1 would be 1:20 or 2 would be 60 and R3 would be 40 what is the current through the entire circuit so that once you find req and you know voltage you can find that so by knowing re you and voltage this is 120 volts we can apply Ohm's law find the current through the battery that's the current through the entire circuit not to find the current through each of the resistors you do I go to be over r v is going to be the same for each of these that's the cool thing about a parallel circuit is that each element in the circuit gets to use the full Voltage no matter how many things you hook up the thing that goes up is the current goes up the more things you hook up the more current is going to flow through your through your battery if your branches of your circuits do you have to be careful about that and then to find the power of the circuit you go back to the battery and you do people's IV for the battery where I is the total current through the circuit and fees the voltage of the battery okay good luck

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