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#1 2014-03-29 04:22:59
Electricity
4 cells of resistance 1/4 Ohm are connected in series with 1 cell has its terminal reversed. The current flowing will be _____ if each cell has EMF 1.5 V and 1 Ohm is the external resistance.
Fill up the blank and tell me how you do it.
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#2 2014-03-29 04:34:33
- ShivamS
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- Registered: 2011-02-07
- Posts: 3,648
Re: Electricity
Technically, it would be zero as cells work only when they are connected with opposite terminals. In this case it is reversed. However, I am pretty sure that the answer that you want involves allowing current to flow when the battery is placed in reverse so:
Remove all the internal resistance of the battery and connect it in series to the circuit, giving:
Total R = 1 + 4(1/4) = 2 ohms
The total potential difference is just the sum of all individual potential differences
Total V = 3*1.5 - 1.5 = 3V
Due to Ohm's law, I = 1.5 amperes
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#3 2014-03-29 04:38:33
Re: Electricity
I got the same thing too.
Technically, it would be zero as cells work only when they are connected with opposite terminals. In this case it is reversed. However, I am pretty sure that the answer that you want involves allowing current to flow when the battery is placed in reverse.
Could it be that it is a trick question?
Besides, why won't it flow?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#4 2014-03-29 04:40:17
- ShivamS
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- Registered: 2011-02-07
- Posts: 3,648
Re: Electricity
It could be a trick question. Were you told in school to just leave it as zero? It's a bit complicated to explain why that happens... We'd have to talk in detail about the voltaic battery cells and so on. I'll try to find a good explanation/diagram online.
Last edited by ShivamS (2014-03-29 04:41:08)
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#5 2014-03-29 04:53:23
Re: Electricity
Thank You.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#6 2014-03-29 05:01:10
- ShivamS
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- Registered: 2011-02-07
- Posts: 3,648
Re: Electricity
This is almost certainly a trick question. You should ask your teacher whether it is an ideal battery with little internal resistance or not or whether it is a "real-life" situation.
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#7 2014-03-29 05:21:59
- Bob
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- Registered: 2010-06-20
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Re: Electricity
hi ShivramS
Why do you say the cells won't do anything? I like your 1.5 amps answer.
See:
http://resources.schoolscience.co.uk/br … h1pg2.html
Bob
ps. We are told the internal resistances are 0.25 ohms.
Last edited by Bob (2014-03-29 05:23:14)
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#8 2014-03-29 19:32:25
Re: Electricity
Hmm, I have tried that in my childhood. It did not work.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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