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Prelim question help (1 Viewer)

Joshmosh2

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Mar 30, 2014
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Just finished my prelim exam, and I have two main questions

If there is a charged plate, with charges X,Y, and Z residing within it. All the charges are equal. X,Y, and Z are located at different positions within the plate. X is closer to the positive side, Z in the middle and Y closer to the negative.

In this case, would the forces exerted on each charge be the same? or will there be greater force on charges X or Y?

Also, one more question

There is a table of voltage and current, and the question said to plot them, and find the resistance.
What was the most appropriate way of calculating it?

I used the gradient method. I selected the first two points and used rise/run.
They then asked if it was ohmic or non-ohmic
I used the gradient method for the next two points, providing a different resistance, so my reasoning was that since the resistance at various points is different, the resister is non-ohmic. However, the points looked relatively aligned. Was I supposed to use the gradient for the line of best fit? thanks.
 

bakstar

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Jun 24, 2013
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In regards to the ohmic vs non-ohmic - If its a line of best fit, aka the lines are generally along the same line, then its ohmic. Whereas if its more of a curve of best fit, exponential curve, then its non-ohmic.

And regarding the charged plate, it do believe the forces are equal but im not sure.
 

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