<img src="./images/loop_in_B_field.png" align="center" style="width: 550px";/> The force on a segment of wire $L$ is $\mathbf{F} = I \mathbf{L} \times \mathbf{B}$ A current-carrying wire loop is in a constant magnetic field $\mathbf{B} = B \hat{z}$ as shown. What is the direction of the torque on the loop? 1. Zero 2. +x 3. +y 4. +z 5. None of these Note: * CORRECT ANSWER: B

The torque on a magnetic dipole in a B field is: $\mathbf{\tau} = \mathbf{m} \times \mathbf{B}$ How will a small current loop line up if the B field points uniformly up the page? <img src="./images/mag_loops.png" align="center" style="width: 800px";/>

Suppose I place a small dipole $\mathbf{M}$ at various locations near the end of a large solenoid. At which point is the magnitude of the force on the dipole greatest? <img src="./images/force_on_mag_dipole.png" align="center" style="width: 600px";/> D) Not enough information to answer E) There is no net force on a dipole Recall: $\mathbf{F} = \nabla (\mathbf{m}\cdot\mathbf{B})$ Note: * CORRECT ANSWER: B