### Author Topic: Battery Question - Circuits In Series  (Read 4074 times)

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#### garriwilson

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##### Battery Question - Circuits In Series
« on: February 16, 2008, 11:24:16 PM »
OK, I think this is really simple, I was just wondering. In a simple circuit let's say there is a 9v battery. It sends 9v to 2 lamps connected in series. Each lamp uses only 2v... Isn't the voltage coming back to the battery's negative terminal supposed to be 0V (zero volts)? What happens when that 1V comes back to the negative terminal?

#### airman00

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##### Re: Battery Question - Circuits In Series
« Reply #1 on: February 16, 2008, 11:25:54 PM »
i believe the lamps will use more than 2V ,they will be brighter than at 2V and might burn out
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#### garriwilson

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##### Re: Battery Question - Circuits In Series
« Reply #2 on: February 16, 2008, 11:29:23 PM »
Oh so no matter how much the voltage of the battery exceeds the limitations of the components, they'll still take it? If the battery is 12v, lamps take 3v each, 2 lamps, will the first lamp have more voltage across it? Or will they still divide it evenly after voltage exceeds its limits?

#### benji

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##### Re: Battery Question - Circuits In Series
« Reply #3 on: February 17, 2008, 08:33:17 AM »
firstival ,what kind of lamp are you using? is there a dc lamp? do you mean leds?
anyways ,its a matter of leds resistance , if they are equal(always) the leds will devide the battery voltage equally
so if you are using a 9 volts battery n connect it to 2 leds connected serially each one would have 4.5 volts across it
and your leds will burn out.
you should always include a resistor in such circuit so the leds will take the voltage they need and the rest of the voltage will come across the resistor
so, the more battery voltage you use the more current you provide and the leds will be brighter
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##### Re: Battery Question - Circuits In Series
« Reply #4 on: February 20, 2008, 07:58:05 AM »
Quote
Isn't the voltage coming back to the battery's negative terminal supposed to be 0V (zero volts)? What happens when that 1V comes back to the negative terminal?
By definition, ground is always 0V. Its impossible for it to be 1V . . .

If this is part of a larger circuit, then perhaps you didn't make your grounds common . . .

• Robot Overlord
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##### Re: Battery Question - Circuits In Series
« Reply #5 on: February 22, 2008, 03:32:20 AM »
OK, I think this is really simple, I was just wondering. In a simple circuit let's say there is a 9v battery. It sends 9v to 2 lamps connected in series. Each lamp uses only 2v... Isn't the voltage coming back to the battery's negative terminal supposed to be 0V (zero volts)? What happens when that 1V comes back to the negative terminal?

There is no such a thing as "this lamp uses 2V of electricity". Lamps (and any other machine) consume/use WATTs,i.e.,power. And they are connect to 2 volts(or more or less). In your case, considering that both lamps are equal, each one of them will be connected to 4.5V. Of course that will problably burn the lamps since them were made for 2V.
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#### Trumpkin

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##### Re: Battery Question - Circuits In Series
« Reply #6 on: February 22, 2008, 10:50:51 AM »
p=V*I. So if you want to calculate what bulb you would need multiply the voltage times the current in your circuit which would equal power in watts, that would tell you what bulb you would need so it wouldn't burn out. Am i right? I'm only twelve so go easy on me.
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• Robot Overlord
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##### Re: Battery Question - Circuits In Series
« Reply #7 on: February 22, 2008, 08:49:19 PM »
Yes, Trumpkin is right. But you ysually doesnt know the current so you can use this: P=IV=V^2/R. Just in case you dont know the voltage but knows the current you can use this: P=I^2*R.
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#### paulstreats

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##### Re: Battery Question - Circuits In Series
« Reply #8 on: February 23, 2008, 07:36:56 AM »
Just to add a little input to this topic. A lot of high voltage circuits include a ballast lamp which is a light that can tollerate a lot of electricity. They are used quite often when coils are used in circuits and their job is to take any excess electricity that the other components dont need, so if the coil breaks down and sends 2000watts more electricity than the circuit would normally cope with, the ballast light absorbs the additional power and lights up

#### garriwilson

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##### Re: Battery Question - Circuits In Series
« Reply #9 on: February 23, 2008, 01:53:53 PM »
Thanks everybody, now it's very clear to me.  So, all the voltage must be used even if the components are not rated for it right?

#### izua

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##### Re: Battery Question - Circuits In Series
« Reply #10 on: February 23, 2008, 02:33:20 PM »
Don't ever, ever use underrated components. Except if you want fireworks
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#### garriwilson

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##### Re: Battery Question - Circuits In Series
« Reply #11 on: February 23, 2008, 07:40:07 PM »
Haha, I got an idea. Overcharge christmas lights on your house...

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#### airman00

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##### Re: Battery Question - Circuits In Series
« Reply #12 on: February 23, 2008, 07:44:09 PM »
Haha, I got an idea. Overcharge christmas lights on your house...

Hello, is this 911?

lol funny

and since they are wired in parallel you'll have individual explosions
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#### paulstreats

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##### Re: Battery Question - Circuits In Series
« Reply #13 on: February 23, 2008, 07:46:48 PM »
apart from the fuse bulb which prevents this sort of thing. Just take it out if you must

#### garriwilson

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##### Re: Battery Question - Circuits In Series
« Reply #14 on: February 23, 2008, 08:00:58 PM »
Haha yea I read that thing about the fuse inside Christmas lights. If one blows, not all of them blow. And they are wired in series. They don't blow because when the light burns out, it short circuits and the current still goes through.

#### airman00

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##### Re: Battery Question - Circuits In Series
« Reply #15 on: February 23, 2008, 08:10:27 PM »
Haha yea I read that thing about the fuse inside Christmas lights. If one blows, not all of them blow. And they are wired in series. They don't blow because when the light burns out, it short circuits and the current still goes through.

depends which type , some are in parallel and have a fuse in the place where you connect it to power , in parallel allows you to have some bulbs blown while others still are on
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