Potential difference between two points in an electric field

  • #1
NoahCygnus
96
2
Homework Statement
In the problem, I have to calculate the potential difference between C and A as in the uniform electric field of magnitude 20 V/m given in the figure.
Relevant Equations
##\Delta V = -\vec{E}\cdot\Delta\vec{r}##
So I have been given a uniform electric field ##\vec{E}=20 V/m## in the direction as show in the image. I have been told to calculate the potential difference ##VC - VA##. According to the teacher (on YouTube) the potential difference ##VC - VA = -10\sqrt{2}V##. But I say it's ##-20 V## as electric field is conservative and I can find potential difference as work done in moving a unit charge from ##A## to ##D## then to ##C##. Potential difference between ##D##and ##A## should be a big zero as we are moving perpendicular to the field and potential difference between ##C## and ##D## is ##-20V## so the overall potential difference between ##C## and ##A## should be ##-20V## and not ##-10\sqrt{2}##.

They used ##\Delta V = -\vec{E}\cdot\Delta\vec{r}##, and put in the values ##\Delta V = -(20)(1)cos(45)=-10\sqrt{2}##
 

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  • #2
Their problem is that the length of the diagonal is not 1 m, it is ##\sqrt 2## m.

Edit: You should probably also link to the relevant video if it is on YouTube.
 
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