Equipotential Lines Homework: Calculating Electric Field Strength

AI Thread Summary
The discussion focuses on calculating the electric field strength at points A and B using equipotential lines. The key formula discussed is E = -ΔV/Δs, where participants clarify that the voltage change should be divided by the distance along the y-axis. For point A, the voltage difference of approximately 10 volts over a distance of 2 cm yields an electric field strength of about 5. Participants emphasize the importance of interpreting the equipotential lines correctly, noting that movement along these lines requires no work. Overall, the conversation helps clarify how to approach the homework problem effectively.
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Homework Statement


The figure below shows the equipotential lines for a uniformly varying electric field.
[PLAIN]https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/Phys1202/fall/homework/Ch-20-Potential/equipotential_lines/equ-lines-1.jpg

A) What is the approximate strength of the electric field at point A?
B) What is the approximate strength of the electric field at point B?

Homework Equations


-E=ΔV/Δs (That's what I think...)


The Attempt at a Solution


I think I have to start off by dividing the voltage by the distance, but besides that I really have no idea on how to start the problem. I'm not just looking for an answer, but if anyone could get me started off I'd appreciate it.
 
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That's exactly what you do, divide the voltage by the distance. For the equipotential of A you seem to go approximately 10 Volts lower for every 2cm of y.
 
Ok, so would it be 15 divided by 3.50 or 15 divided by 5.70? I tried both these numbers, both turn out to be wrong answers.
 
Where did you get 15 from?
 
Point A is located between 10 V and 20 V and it is kinda in the middle. So i tought it would be 15, but now I am totally confused! :/
I don't know how to read these graphs, my teacher never really talked about them.
 
Oh, yeah, you're just interpreting the graphs wrong. Lines of equipotential show that there would be no work to move a particle along one of the lines. So you can see from these graphs that the lines of equipotential is flat along the x axis, so there's no change ever. Ignore the x. Now, in the y-axis we do get change, and that change varies, so there must be an electric field in the direction of y.

E=-∆V/∆s
so approximate the first point A by looking at the change along the y direction for that region
E=-(10-20)/(4.2-2.2)=5

I'll let you do point B.
 
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Thank you so much man. Now not only I know how to do read the graph, I can do the rest of the homework. :)
 
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