# Contour map help

1. Aug 21, 2008

### fredrick08

1. The problem statement, all variables and given/known data

50V | /\
| / \
| / \
|/ \
0 |---1------2---3---- x(cm)
| \ /
| \ /
| \/
-50V|

best i could do, sorry dont know how to open picture up... its not to scale obviously but i think everything u need is there, i need to make a contour map of this function on the xy plane, 0=<x=<3cm and -5=<y=<5cm... show and label the -50V, -25V, 0V, +25V and +50V equipotential lines....

ive tried to understand what this means form other contour maps i have drawn, but i just dont understand what it wants me to do.... can someone plz help me, i would greatly appreciate a graphical representation. i know they have to be an equal distance apart but i dont understand the -5 and 5cm and have no idea what direction they in

2. Aug 21, 2008

### fredrick08

omg sorry... it wont show up properly wat i typed...

3. Aug 21, 2008

### fredrick08

4. Aug 21, 2008

### HallsofIvy

Staff Emeritus
your function appears to depend only on x. If that is the case then your contour map will consist of horizontal straight lines.

5. Aug 21, 2008

### fredrick08

oh ok so they are just horizontal... that make more sense, ok well wat the -5 and 5cm in y dir mean??? im really lost there... so is it just 5 evenly spaced horizontal lines??? but where bouts do they start and finish?

6. Aug 21, 2008

### fredrick08

plz can someone explain, my last question to me?

7. Aug 21, 2008

### fredrick08

is this right then??

8. Aug 21, 2008

### fredrick08

can anyone help?

9. Aug 21, 2008

### fredrick08

ok ive been thinking, and i know wat ive done makes no sense at all, are the line meant to go in order, like they r in the graph??

10. Aug 21, 2008

### fredrick08

ok i got no idea now..... ive drawn that many maps.... and i just cant seem to work out how the lines go??? plz someone help

11. Aug 21, 2008

### fredrick08

maybe like this?? the values didnt come out rite they are meant to align with the horizontal lines.

12. Aug 21, 2008

### fredrick08

plz anyone????

13. Aug 21, 2008

### LowlyPion

What is it you are trying to contour? From your drawings it is not clear to me. Perhaps that's why you've gotten so little response?

What contour lines are you trying to show? Iso-voltage lines on an xy map?

What is the table of data points you are supposed to map?

14. Aug 21, 2008

### fredrick08

yes i know what u mean, im trying to draw the electric potential contour map of the above function... i have no idea what this means.... the first part of the question o had to find Ex vs x... which i did easy.... but this part is confusing.... apparently the equipotential lines are evenly spaced horizontal lines. but im not 100% sure, but it makes sense it is just a linear graph

15. Aug 21, 2008

### HallsofIvy

Staff Emeritus
fredrick08, I made a rather foolish mistake. Since the values vary with x but not y, your contour map should be vertical lines not horizontal lines as I said before.

You should have, for example, a vertical line at x= 0 labeled V= 0, at x= 0.5 labeled V= 25, at x= 1.0 labeled V= 50, at x= 1.5 labeled V= 0, at x= 2.0 labeled V= -50, at x= 2.5 labeled V= -25 and at x= 3.0 labeled V= 0.

16. Aug 21, 2008

### fredrick08

the questions says, also that the potential is independent of y and x.

Draw a contour map of the potential in the xy plane in the square region 0cm=<x=<3cm and -5cm=<y=<5cm, show and label the -50V, -25V, 0V, 25V and 50V equipotential lines... that is allt he question says.... does it make sense??

17. Aug 21, 2008

### fredrick08

sorry hallsofivy, i dont understand what u mean..... but what do i do in the y dir.... is -5 and 5 just numbers to make it look nice lol???

18. Aug 21, 2008

### LowlyPion

By that if you mean the zig zag up/down function in your first picture, then that function is invariant in Y. Hence as just pointed out by Halls of Ivy for any X the contour line in the Y will be straight up and down across all the values of Y. The values of those lines will follow the values of your "function". You will have a "0" contour that overlaps the Y Axis, a 50V line that runs up through 1, a "0" that runs through the X crossover of your function at 1.5, a -50 that runs through 2 and another "0" that runs through 3.

19. Aug 21, 2008

### fredrick08

oh ok thankyou i understand now... sorry im stupid lol

20. Aug 21, 2008

### LowlyPion

Oh and I see you will need to add the 25v and -25v intermediate lines between the 0 and 50v lines as well.

Good luck.