- #1

MyoPhilosopher

- 41

- 4

- Homework Statement
- A compass needle has a magnetic moment of 𝜇. At its location, the magnitude of the Earth’s magnetic field is 𝑩 northward at 𝜃 below the horizontal. Identify the orientations of the needle that represent (a) the minimum potential energy and (b) the maximum potential energy of the needle–field system. (c) How much work must be done on the system to move the needle from the minimum to the maximum potential energy orientation?

- Relevant Equations
- ΔU = -μBcos(θ)

Sorry if I am asking in the wrong fashion as I am new.

The above questions are easily solvable:

1) U = -μBcos(0)

2) U = -μBcos(180)

3) W = ΔU = 2) - 1)

My question is more related to some theory: where is this work/energy coming from since a magnetic force, to my knowledge can't do "work"?

What force is doing -W (minus W), is it simply the magnetic field, or is there another concrete equation to demonstrate what exactly is happening.

Thank you for anyone that can explain or possibly ask me directional questions

The above questions are easily solvable:

1) U = -μBcos(0)

2) U = -μBcos(180)

3) W = ΔU = 2) - 1)

My question is more related to some theory: where is this work/energy coming from since a magnetic force, to my knowledge can't do "work"?

What force is doing -W (minus W), is it simply the magnetic field, or is there another concrete equation to demonstrate what exactly is happening.

Thank you for anyone that can explain or possibly ask me directional questions