(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A wire along the x-axis carries currentIin the negative x-direction through the magnetic field

[tex]\vec{}B[/tex] = B_{0}*(x/L) [tex]\hat{}k[/tex] 0[tex]\leq[/tex]x[tex]\leq[/tex]L

= 0 elsewhere

Part a was to draw a graph of B versus x over the interval -L[tex]\leq[/tex]x[tex]\leq[/tex]L, which I did.

b. Find an expression for the net force F_{\rm net} on the wire. Express your answer in terms of the variablesI, L, and B_{0}

c. Find an expression for the net torque on the wire about the point x = 0.

Express your answer in terms of the variablesI, L, and B_{0}

2. Relevant equations

F_{net}=I*L*B*sin[tex]\alpha[/tex]

[tex]\tau[/tex]_{net}=I*L^{2}*B*sin[tex]\alpha[/tex]

3. The attempt at a solution

I thought that becauseIis carried in the -[tex]\hat{}i[/tex] direction and B points in the [tex]\hat{}k[/tex] direction that [tex]\alpha[/tex]=90 degrees, meaning I would be multiplying by 1. However, for both parts, when I submitI*L*B_{0}andI*L^{2}*B_{0}, respectively, the website says "Your answer either contains an incorrect numerical multiplier or is missing one."

For part b I've tried submitting -I*L*B_{0}because actually calculating I[tex]\hat{}L[/tex] X [tex]\hat{}B[/tex] yields a negative answer, but that didn't work either.

I've also tried to use x in my answer, and the website says the correct answer doesn't depend on it.

Any help would be much appreciated!

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

2. Relevant equations

3. The attempt at a solution

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Force and torque on a wire carrying a current

**Physics Forums | Science Articles, Homework Help, Discussion**