Physics 12 Help- Electomagnetism and Torque

[sweatpants]

Homework Statement

If you were given this question: http://img40.imageshack.us/img40/975/picture7we.png
how would you go about solving it?

Homework Equations

I found a formula that makes this question seem a lot easier. Torque = NIAB. however, this formula is not on the formula sheet that is approved by the school so I am not supposed to know about it unless i figure out how to derive it. Does anyone know how this formula was derived?

The Attempt at a Solution

 

[Dick]

Homework Statement

If you were given this question: http://img40.imageshack.us/img40/975/picture7we.png
how would you go about solving it?

Homework Equations

I found a formula that makes this question seem a lot easier. Torque = NIAB. however, this formula is not on the formula sheet that is approved by the school so I am not supposed to know about it unless i figure out how to derive it. Does anyone know how this formula was derived?

The Attempt at a Solution

Try http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magmom.html

 

[sweatpants]

Try http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magmom.html

Hmmm. I've never actually heard of a magnetic dipole moment or its potential energy. Apparently this question is supposed to be solved using solely equilibrium equations and electromagnetism equations which don't already include torque.

Thanks for trying to help though.

 

[OmCheeto]

Hmmm. I've never actually heard of a magnetic dipole moment or its potential energy. Apparently this question is supposed to be solved using solely equilibrium equations and electromagnetism equations which don't already include torque.

Thanks for trying to help though.

Is Force = Current x Length x B-field on your approved formula sheet?

Of course, you'll need to add the equation for torque to come up with the answer.

 

[asteriatic]

To solve this question, you would first need to recognize that it involves electromagnetism and torque. This means that you will need to use equations and principles from both of these areas of physics. The given formula, Torque = NIAB, is a commonly used formula in electromagnetism, where N is the number of turns in the coil, I is the current, A is the area of the coil, and B is the magnetic field strength. However, as you mentioned, this formula may not be on the approved formula sheet, so it is important to understand how it was derived.

To derive this formula, you would need to use the principles of electromagnetism, specifically Faraday's law and the Lorentz force law. Faraday's law states that the induced electromotive force (EMF) in a closed circuit is equal to the rate of change of the magnetic flux through the circuit. In this case, the magnetic flux is equal to the product of the magnetic field strength and the area of the coil, so we can write this as:

EMF = -d(BA)/dt

The negative sign indicates that the induced EMF will oppose the change in magnetic flux. Next, we can use the Lorentz force law, which states that the force on a charged particle in a magnetic field is equal to the product of the charge, velocity, and magnetic field strength. In this case, the charged particles are the electrons in the wire, and the force they experience will cause them to move in a circular motion around the axis of the coil. The direction of this force can be determined using the right-hand rule.

Now, we can combine these two equations to find the torque on the coil. Torque is defined as the force times the lever arm, so we can write this as:

Torque = F x r = qvB x r

Since we are dealing with a coil, we can assume that the radius of the coil is equal to the radius of the circular motion of the electrons. We can also substitute qv for the current, so we get:

Torque = NIAB

This is how the formula for torque in an electromagnet was derived. It is important to understand the principles and equations behind the formula, rather than just memorizing it. I encourage you to continue exploring and understanding the concepts of electromagnetism and torque in order to become a better physicist.