# Homework Help: Trouble determining the slope of the graph!

1. Apr 8, 2013

### riseofphoenix

For the slope, I got 0.4532 and for B, I got 74.09, but they're both wrong! And my excel program keeps crashing everytime i try to print screen it!
This is really urgent and I don't know who else to turn to because this is due very very soon and I'm desperate!!

2. Apr 8, 2013

### rock.freak667

Check your R^2 value and see if it is close to 1. When I plot your values I don't get anything near 0.4 for the gradient. Does your answer require a specific set of units?

3. Apr 8, 2013

### riseofphoenix

No :(
My computer keeps acting up whenever I try to print screen and save the excel file...
What numbers did you get?

4. Apr 8, 2013

### riseofphoenix

You still there?

5. Apr 8, 2013

### rock.freak667

Around 0.008 N/cm or so.

6. Apr 8, 2013

### riseofphoenix

I submitted "0.008 N/cm" but webassign says it's incorrect :( :'(
That must mean my B is wrong too... :(

7. Apr 8, 2013

### rock.freak667

You might actually need to post your excel graph so we can see what is happening.

8. Apr 8, 2013

### Staff: Mentor

Try 0.85 N/m.

Also, I don't think that the parameter you call "length" is not the actual length of the wire, since, on the graph, when the force goes to zero, the "length" goes to zero. Therefore, I can only conclude that the parameter that your teacher called length in the table is actually displacement relative to the length under no load. If the parameter really is displacement, then you can add the point 0,0 to your graph for added accuracy.

9. Apr 8, 2013

### riseofphoenix

Oh it worked! Thanks!!

So all I need for B is do,

B = Faverage / IaverageLaverage
B = (0.02075)/(892.75 mA)(0.02525 m)
B = 0.02075/22.54
B = 0.000920586
B = 920 T

10. Apr 8, 2013

### riseofphoenix

Fot Question 2,

I got the slope correct. It's 0.0339.

But how do I find B, given L = 4.1 cm?

This is what I did (I chose any value for F and I from the table):
B = F/IL
B = (0.0158 N) / (0.48 A)(0.041)
B = 0.0158/0.01968
B = 0.802 N/a

"INCORRECT"

:(

11. Apr 8, 2013

### riseofphoenix

You still there? :(

12. Apr 8, 2013

### riseofphoenix

You still there? :(

13. Apr 8, 2013

### riseofphoenix

Oh no :( :( :(

14. Apr 8, 2013

### riseofphoenix

15. Apr 8, 2013

### riseofphoenix

Anybody still here?