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Electric potential of electron

  1. Jun 9, 2015 #1
    1. The problem statement, all variables and given/known data

    An electron is placed in an xy plane where the electric potential depends on x and y as shown in the figure (the potential does not depend on z). The scale of the vertical axes is set byVs = 500 V. In unit-vector notation, what is the electric force on the electron?
    https://www.facebook.com/photo.php?fbid=1403786173283706&set=a.1403786203283703.1073741827.100009570105613&type=1
    2. Relevant equations


    3. The attempt at a solution
    I tried evaluating the graph and seeing as it is a straight line for both the x and y components of the E field i was thinking i could get a partial derivative
    ∂V/∂x=-(-500v/0.4m)=1250N/C
    ∂V/∂y=-(100V/.4m)=-250N/C
    I think this is where i went wrong.
    anyhow, I went on to find the magnitude and direction of the E field
    |E|=√(1250^2+250^2)=1274.75N/C
    θ=tan^-1(-250/1250)=-11.31°
    the next step given the force on an electron as F=qE
    finding this for the separate components in vector notation give q=1.6*10^-19C
    so F=(1.6*10^-19C)*[(1250N/Ci), (-250N/Cj)]
    it is not the right answer so my understanding is failing at a point
    thankyou
     
  2. jcsd
  3. Jun 9, 2015 #2

    mfb

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    Including the picture like this does not seem to work, but this link should work.
    How did you get those 500 V and 100 V? The difference between 0 and 0.4 m looks larger in both pictures.
     
  4. Jun 9, 2015 #3
    oh... derpy me thank you for pointing out my mistake... I know what i did now... i thought that was were i went wrong but i just could not see what it was
     
  5. Jun 10, 2015 #4

    SammyS

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    Or maybe this way:

    https://scontent-ord1-1.xx.fbcdn.net/hphotos-xta1/v/t1.0-9/11391362_1403786173283706_627839923534487902_n.jpg?oh=61df4a57a6442947a541c4582b4e1ad1&oe=562D9CDD
    ... so all can see it.

    Added in Edit:
    It might be helpful to explain what I did to make this image visible:

    I used the Link provided by mfb .
    I'll speculate that mfb looked into the Original Post someway in order to obtain the link.​

    I right-clicked on the image which appeared when I followed the link and chose "Copy Image"

    Then I simply "Paste"-d the image into the message editor .

    An alternative would have been to copy the image to a file on my computer, then use the upload feature at the bottom of the message editor. This method would have the advantage of ensuring that the image will be accessible even if the original image gets deleted or moved or whatever. -- but I was in a hurry and/or was being stingy with my disk space.
     
    Last edited: Jun 10, 2015
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