1. The problem statement, all variables and given/known data 1. A wire of length L and carrying current I is bent into a square loop to form a magnetic dipole. This dipole is then oriented in a uniform magnetic field of magnitude B such that the dipole is in its lowest energy state. What is the value of the dipole's energy with this orientation? A. 0 B. -ILB C. -IL2B D. -1/4IL2B E. -1/16IL2B 2. A negative point charge moves with a velocity v next to a long, straight wire carrying a current I upward (in the plane of the page. Because of the charge's motion, there exists a force on the charge to the left. The charge must be moving: A. to the left B. to the right C. upward D. downward E. out of the page These were a couple of the multiple choice questions from a quiz I had in my physics course the other day and I wanted to go over them with someone on here and see if my logic on them was correct or not so I'll know for the final later on. 2. Relevant equations For question 1: μ = IA U = -μ x B cos θ F = IL x B For question C: F = qv x B F = IL x B 3. The attempt at a solution For question 1, I believed that answer to be C. I wasn't sure how to take into account when we're told that the dipole is in its lowest energy state. But I was thinking that since we a square loop, that in taking μ = IA, that A would be equivalent to L2 so we'd get μ = IL2 from that. Then to incorporate energy state, since the equation for energy is U = -μ x B, that the final answer would be U = -IL2 x B. For question 2, we're told that the moving charge is negative but that the current moves in an upward direction. I was thinking that a moving charge with a given velocity would be equivalent to current if the charge is positive. Since we're told that the point charge is negative, I rationalized that it must be moving in an opposite direction to the current and hence, would be moving in a downward direction, so answer D. Thanks so much!