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Electric Potential in a region of space

  • #1

Homework Statement


The electric potential in a region of space is
render?texml=V+%3D+%5Cfrac%7B350%7D%7B%5Csqrt+%7Bx%5E2+%2B+y%5E2+%7D%7D.gif

, where x and y are in meters. What is the strength of the electric field at (x,y)=(2.1m,2.7m)?
The electric force is in V/m.

Homework Equations


E = -grad(V)
E = -dV/ds

The Attempt at a Solution



I know that i have to find the partial derivatives of the x and the y but im not sure on how to get the answer from the equation given. I was thinking of making the square root into the exponential of 1/2 and then raising that to -1 to get ride of the fraction and then taking the derivatives of that but i keep getting the wrong answer. Anybody have suggestions of help they can give me please. Thanks.
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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Welcome to PF!

render?texml=V+%3D+%5Cfrac%7B350%7D%7B%5Csqrt+%7Bx%5E2+%2B+y%5E2+%7D%7D.gif

…I know that i have to find the partial derivatives of the x and the y but im not sure on how to get the answer from the equation given. I was thinking of making the square root into the exponential of 1/2 and then raising that to -1 to get ride of the fraction and then taking the derivatives of that but i keep getting the wrong answer. Anybody have suggestions of help they can give me please. Thanks.
Hi quietriot1006! Welcome to PF! :smile:

(btw, please use the LaTeX provided, rather than importing images of equations)

Just use the Chain Rule for differentiation …

you know how to differentiate 1/√x, don't you? :wink:
 
  • #3
Thanks for the welcome. Im still not getting the answer. Maybe im doing the chain rule incorrectly. What would i use for u or g(x) and h(x)?
 
  • #4
tiny-tim
Science Advisor
Homework Helper
25,832
251
Thanks for the welcome. Im still not getting the answer. Maybe im doing the chain rule incorrectly. What would i use for u or g(x) and h(x)?
(x2 + y2) :smile:
 
  • #5
I keep getting the same asnwer, -127 V/M and its not the right answer. What else can i do?
 
  • #6
tiny-tim
Science Advisor
Homework Helper
25,832
251
I keep getting the same asnwer, -127 V/M and its not the right answer. What else can i do?
Show us your calculations, and then we can see where the mistake is. :smile:
 

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