The magnetic field inside a solenoid is 8.617 mT. If this solenoid sits with its central axis perpendicular to a 30 mT magnetic field, what is the magnitude of the torque on the solenoid
For the torque on a solenoid in field B oriented at angle a, see
http://library.thinkquest.org/16600/advanced/magneticfields.shtml
The torque G is given is in terms of N I A, where N is the number of solenoid turns or area A, and I is the solenoid current. See if you can relate that to the solenoid-produced field
To find the magnitude of the torque on the solenoid due to the external magnetic field, you need to use the equation:
Torque = Magnetic Moment × External Magnetic Field
The magnetic moment of a solenoid is given by the equation:
Magnetic Moment = Magnetic Field × Area × Number of Turns
To find the magnetic moment, you need to know the area and the number of turns of the solenoid. Unfortunately, that information is missing in the given question. Without the area and number of turns, it is not possible to calculate the magnetic moment and thus the torque.
Please provide the missing information, and I'll be happy to help you calculate the torque on the solenoid.