Electrical – The slope of a graph

currenthomeworkvoltage

What does the slope in this graph present
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I know this might be a silly question, but my answer was:

slope = VI = Pw (Pw is power)

And the answer in my text book was differet from mine, it was:

slope = -r (r is the internal resistance of the battery)

And I think the book answer was related with the equation:

Vb = V -Ir (where Vb is the emf of the battery, V is the voltage across the battery, (I) is the intensity of current and r is the internal resistnce.

So, are the two answers correct? Or it is only one?

Best Answer

The slope of a graph goes as follows:

slope=dx/dy

The voltage is here on the Y-axis and the current is on the X-axis. As I grows (so dx > 0), V decreases (dy<0). If you enter this in the formula you get.

slope=-V/I

Ohm's law states that R=V/I.

So this means that the slope of this curve equals -R.

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