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Mad Scientists Science and Mathematics discussion-- theories, arguments, citations, proofs and pudding.

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 #1 
Old 2008-09-01, 04:20
Pingy Pingy is offline
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Default Charge, Voltage, Current, Energy, and Time

So I have this problem I'm trying to understand.

In part A, I have to find the total charge transferred to a battery. I am given a graph of voltage over time. From the way the problem is stated, its quite clear the method of solution is to find the area under the curve.

In part B, I have to find the total energy transferred. I am given a graph of current over time and I am pretty sure the method of solution is the same.

A few questions:

Its late at night, I'm tired, so excuse me if I sound retarded.

How is charge equal to the integral of dV/dt?
How is energy equal to the integral of dI/dt?

I know that i = dq/dt and v = dw/dq also p = dw/dt.

I should make sure that I am using a time scale of seconds and not kiloseconds in doing my calculations, correct?
 #2 
Old 2008-09-05, 14:19
Pingy Pingy is offline
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Default Re: Charge, Voltage, Current, Energy, and Time

Its been a few days...seriously nobody can help me out??
 #3 
Old 2008-09-05, 19:52
MadMaster MadMaster is offline
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Default Re: Charge, Voltage, Current, Energy, and Time

Quote:
Originally Posted by Pingy
Its been a few days...seriously nobody can help me out??


Dood, you need to understand what Madscientists is.


A bunch of kids.



Sucks for you.
 #4 
Old 2008-09-06, 03:24
Regular
 
Berkshire, UK
Default Re: Charge, Voltage, Current, Energy, and Time

So I have this problem I'm trying to understand.

In part A, I have to find the total charge transferred to a battery. I am given a graph of voltage over time. From the way the problem is stated, its quite clear the method of solution is to find the area under the curve.

In part B, I have to find the total energy transferred. I am given a graph of current over time and I am pretty sure the method of solution is the same.


I think you're all mixed up. Can you post the question? The total charge is equal to the Integral of current with respect to time. You can't work it out just from the voltage and time as you don't know how much charge is being transfered.


How is charge equal to the integral of dV/dt?
How is energy equal to the integral of dI/dt?


Also, when you have the area under the curve, that not equal to Integral (dy/dx), its equal to Integral (y dx).
 
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