Cells in series

I am trying to build a circuit of cells in series. These are supposed to be D cells here https://www.circuitlab.com/circuit/5f4gn2/series/

I was expecting a large output in Amps, am I missing something fundamental?

by harrydeshpande
May 04, 2015

What's the problem?

You have 7*1.5V = 10.5V open circuit voltage in series with 7*0.3 Ohms = 2.1 Ohms.

Apply Ohms Law: V = I/R

Therefore: I = V/R

10.5V/2.1 Ohms = 5A

which is what you have showing on the Ammeters.

by signality
May 05, 2015

Thanks. Yes, you are right. I guess I was thrown off because of 1st ammeter in the series that also shows 5 amp.

Actually I am trying to find answer to a different question. You tube has this thomas edison lamp experiment where one burns a graphite led with 6 D cell batteries. This works with 6 D batteries in series but not with 1 9 V alkaline battery. I think it has something to do with 9 V battery is just 6 1.5v batteries under the hood. However, I am not sure what is the real technical reason. Obviously 9V battery is outputting less current.

Appreciate your comments.

by harrydeshpande
May 05, 2015


Both ammeters will read the same current because they're in series.

That's what being in series means.

As for the "thomas edison lamp experiment where one burns a graphite led ", I think you are confusing terminology.

I suspect the experiment passes current through a graphite filament.

In the absence of a link to the You Tube video, I'd guess that the experiment works with 6 D cells because a D cell has a lower internal resistance that the little 1.5V cells in a 9V battery (but what size: PP3?). Hence the 6 D cells in series can deliver a higher current into a very low resistance load that a small 9V battery.

The 6 D cells will also be able to deliver that current for longer than the small 9V battery.

Probably with less self-heating that would raise the internal resistance too.

by signality
May 05, 2015

Thanks a lot :)

This is the experiment I was talking about https://www.youtube.com/watch?v=DOrebc3hocA

your explanation makes sense.



by harrydeshpande
May 05, 2015

What,s Ohms law,and how can I remember it or use it. Jack

by Jackturner103
August 27, 2015


Google is your friend here. Please have a look at:



by signality
August 27, 2015

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