A2L Item 229
- Description: Identify the direction of the magnetic field at the center of a current loop.
- Goal: Hone the right-hand-rule for vector cross products
- Source: 283-640 B direction from wire loop
- Keywords: Current, Electromagnetism, Magnetic Field, Right-Hand Rule
The question for students:
The diagram shows a circular wire loop of radius R carrying current I. What is the direction of the magnetic field, B, at the center of the loop?
- Left
- Right
- Up
- Down
- None of the above
Commentary for teachers:
Answer
(3) This is the best response given the choices. The question poses little difficulty for students who have learned about the magnetic field of current loops as a magnetic dipole. For these students this question just confirms their knowledge. For students who are trying to apply the Biot-Savart law to the loop as a set of current elements the question is more challenging.