Electrical components connected between cells

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sorax123
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Hi all,
I would appreciate a little guidance on some circuit theory. I was wondering how a circuit behaves when there are, say two identical 10V cells, and a 1Ω bulb happily sitting in series, but then one connects another identical bulb between the two cells. Obviously the current in the first circuit would be 20A, with the pd across the bulb being 20V. But how would the current and pd values change when the second bulb is connected? I have pondered this for a while, but am unsure what to consider in parallel and hence the currents and pd of each bulb. Would be great for someone to give me a little insight.
Thanks
 
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Hi sorax123. A sketch of what you have in mind would have left readers in no doubt about what you are pondering. It sounds as though the pair of identical bulbs are in parallel? If so, then each sees the 20V across its terminals, so each draws 20A. The batteries, I am assuming, can be considered ideal.)

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http://img836.imageshack.us/img836/3228/19k.png

This should give an idea.
Thanks
 
Last edited by a moderator:
sorax123 said:
Hi all,
I would appreciate a little guidance on some circuit theory. I was wondering how a circuit behaves when there are, say two identical 10V cells, and a 1Ω bulb happily sitting in series, but then one connects another identical bulb between the two cells. Obviously the current in the first circuit would be 20A, with the pd across the bulb being 20V. But how would the current and pd values change when the second bulb is connected? I have pondered this for a while, but am unsure what to consider in parallel and hence the currents and pd of each bulb. Would be great for someone to give me a little insight.
Thanks

Between the cells? So the bulb is connected in series with the cells? If so, then the entire circuit is a series circuit. The resistance in the circuit is 2 ohms, applied voltage is 20 volts, so the current is 10 amps. Each bulb has 10 volts of voltage drop across it, adding up to the required 20 volts of applied voltage.
 
As soon as you get more than tho or three components in a circuit, you really have to use tools like Kirchoff's Laws to find what is going to happen. Just chatting about the problem is unlikely to get anywhere - it's a bit like dealing with money - the Maths will give you an answer. 'Understanding' will only come from familiarity with the Maths and the results it produces.
 
Thanks for replies. The cells in the picture were meant to be 10V each, but having done some more thinking and problems today i think I've gotten to the bottom of it. Using Kirchoff's laws one can treat it as 2 series circuits and then "sum" them in a sense. I think this would be the easiest way to tackle it. Thanks