Practice Test 11

A wire segment of length $L=0.25,\text{m}$ carries $I=6.0,\text{A}$ upward through a uniform magnetic field $B=0.30,\text{T}$ directed to the right. Moving charges in the wire create magnetic fields, but the external field exerts a magnetic force on the current: $\vec F=I,\vec L\times\vec B$. Use the right-hand rule for $\vec L\times\vec B$. Refer to the scenario above. What is the direction of the magnetic force on a positive charge moving as described?

A rectangular current loop (height $0.10,\text{m}$, width $0.060,\text{m}$) lies in a uniform magnetic field $B=0.40,\text{T}$ to the right. Current $I=3.0,\text{A}$ flows clockwise as viewed from above; moving charges in the wire create magnetic fields, and the loop experiences forces from the external field via $\vec F=I,\vec L\times\vec B$. The loop’s plane is vertical, so its area vector points north. Refer to the scenario above. Determine the net force on the loop in the given magnetic field.