Calculating Torque on a Circular Loop in an External Magnetic Field

[Kris1120]

Homework Statement

A current of 6.1 A is maintained in a single circular loop having a circumference of
110 cm. An external magnetic field of 5.5 T is
directed such that the angle between the field
and the plane of the loop is 42◦.
Determine the magnitude of the torque exerted on the loop by the magnetic forces acting upon it.
Answer in units of N · m.

Homework Equations

torque = N*I*A*B*sin(theta)

A=pi*r^2

C=2*pi*r

The Attempt at a Solution

r=1.1/(2*pi)
= 0.17507 m

A=pi*r^2
=pi*(0.17507 m)^2
=0.096288 m^2

torque = 1 loop * 6.1 A * 0.096288 m^2 * 5.5 T * sin(42)
= 2.1616 N*m

 

[alphysicist]

Hi Kris1120,

Homework Statement

A current of 6.1 A is maintained in a single circular loop having a circumference of
110 cm. An external magnetic field of 5.5 T is
directed such that the angle between the field
and the plane of the loop is 42◦.
Determine the magnitude of the torque exerted on the loop by the magnetic forces acting upon it.
Answer in units of N · m.

Homework Equations

torque = N*I*A*B*sin(theta)

I believe you make an error later in applying this equation. What does the theta in this equation represent?

 

[Kris1120]

Oh I have to subtract theta from 90! Thanks!