# Magnetic forces between parallel wires

1. Dec 4, 2007

### aliaze1

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

What is the force magnitude on the first, second, and third wires in the figure?

2. Relevant equations

0L I1 I2)/(2πd)

μ0 = 1.2566*10-6

3. The attempt at a solution

Substituting 0.5 as L, 0.02 as d and 10 as I1 and I2 I get 5*10-4,
which comes up as incorrect...what am I doing wrong?

thanks!

2. Dec 4, 2007

### rock.freak667

well if you did some more about current carrying conductors.
you may come across the formula

$$F=\frac{\mu I_1 I_2 l}{2 \pi d}$$

but are you sure you converted cm to m?

3. Dec 4, 2007

### aliaze1

yea that us the formula i used...and i converted everything....the numbers i put in post 1 are the numbers i used for d and L respectivly

4. Dec 4, 2007

### rock.freak667

What is the correct answer? well....you would have to find the resultant force on wires 1 and 3...

5. Dec 4, 2007

### aliaze1

and since the wires are the same, wouldnt some cancel eachother out? (due to the direction of the current)

6. Dec 4, 2007

### aliaze1

well the force in the second wire zero

7. Dec 4, 2007

### rock.freak667

yes the force in the 2nd wire is zero, so you should have to only find the force of attraction of wires 1 and 3...

EDIT: thing to remember...like currents attract, opposite repel

Last edited: Dec 4, 2007
8. Mar 28, 2010

So the just say that the first wire was going in the opposite direction to the other 2 wires... How would u calculate the force acting on wire 1 due to wire 2 (and wire 2 was going the opposite direction) and 3 ?

1<---
2 --->
3 --->

Last edited: Mar 29, 2010