I in this question: Four Wires

[OsDaJu]

Homework Statement

http://s27.photobucket.com/albums/c191/oscar888/?action=view&current=LONCAPA.gif

The four wires that lie at the corners of a square of side a= 3.50 cm are carrying equal currents i= 2.10 A into (+) or out of (-) the page, as shown in the picture.

Part A: Calculate the y component of the magnetic field at the center of the square. ( I already got the answer for this one) 4.80×10-5 T

Part B: Calculate the x-component of the force on a 1.0-cm long piece of the lower right-hand wire, due to the other three wires.

Homework Equations

B=(mu*I)/(2*pi*r)
mu=4*pi*a0^-7 T*m/A

The Attempt at a Solution

I need help in the second part. I don't know where to start.

 

[LowlyPion]

I need help in the second part. I don't know where to start.

Welcome to PF.

You will need to solve by superposition for the B field as in a).

Then you will want to take into account the length of the wire segment in determining the force

F = IL X B

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html#c1

 

[OsDaJu]

Okay, so I know that B is always perpendicular to Force so B2 is zero in the y direction, F2 is zero in the x direction.
then the superposition is:

B total = B1y + B3y
B total = μI/(2π0.0350)*1/√2 + μI/(2π0.0350)
B total = 2.0485*10^-5 T

Using the force formula,

F = BIL
=2.0485*10^-5 *2.1*0.01= 4.3019*10^-7 N

I did all of this and I got the wrong answer, what am I missing??

P.S: sorry for the delay I had a busy week.

 

[LowlyPion]

Okay, so I know that B is always perpendicular to Force so B2 is zero in the y direction, F2 is zero in the x direction.
then the superposition is:

B total = B1y + B3y
B total = μI/(2π0.0350)*1/√2 + μI/(2π0.0350)
B total = 2.0485*10^-5 T

Using the force formula,

F = BIL
=2.0485*10^-5 *2.1*0.01= 4.3019*10^-7 N

I did all of this and I got the wrong answer, what am I missing??

P.S: sorry for the delay I had a busy week.

What you want is the x-directed force component.

The B-Field is a vector field, and the force component from the diagonal has a cos45 factor still needed to normalize it to x.

Btotal = 1.2 * 10^-5 + (.707)(.8 * 10^-5)

 

[OsDaJu]

Thank you!