A2L Item 179
- Description: Identify the correct statement(s) regarding the magnetic field of a current carrying wire.
- Goal: Recognizing the properties of magnetic fields
- Source: 283 - field of wire
- Keywords: Current, Electromagnetism, Magnetic Field
The question for students:
Oersted discovered that there is a magnetic field in the space around wires carrying currents. Consider a long thin straight wire with a current I. Which of the following statements about the magnetic field lines is true?
- Field lines are parallel to the wire.
- Field lines are perpendicular to the wire.
- Field lines are directed radially away from the wire.
- Field lines are circles centered on any point on the wire.
- A only
- B only
- C only
- D only
- A and C only
- B and D only
- B and C only
- None of them is true.
Commentary for teachers:
Answer
(6) It is important to elicit reasons that students selected any of the other responses. Rather than telling the correct answer have students draw the field lines. Often they are able to reproduce pictures they have seen but cannot describe the fields in words.