# Magnitude in a rectangular loop

1. Dec 14, 2006

### ervillalobos

1. The problem statement, all variables and given/known data
The rectangular loop has a mass of .15 g per centimeter of length and is pivoted about side ab on a frictionless axis. The current in the wire is 8.2 A in the direction shown. Find the maggnitude and direction of the magnetic field parallel to the y-axis that will cause the loop to swing up until it's plane makes an angle of 30 degrees with the yz plane.

2. Relevant equations

torque=IBAsin(phi)
I=current
B= Magnitude
30 degrees
A= area (8cm*6cm)=48cm^2 => .48m^2

3. The attempt at a solution

using the right hand rule i know the direction is in the + y-direction.
with the equation i have, i don't how to fit the mass of the loop. so then i was trying to find the force but lack enough information from the problem. please help!

2. Dec 14, 2006

### ervillalobos

side ab is on the z-axis

3. Dec 14, 2006

### ervillalobos

NEED SERIOUS HELP!

4. Dec 14, 2006

### ervillalobos

side ab lies on the z axis

5. Dec 14, 2006

### ervillalobos

how can i use mass in this problem?

6. Dec 14, 2006

### OlderDan

The mass of the loop comes in as part of the gravitational force acting on the loop. While the magnetic field is responsible for the torque in one direction, gravity provides an opposing torque that keeps the loop in equilibrium.