AP · AP C:E&M · multiple choice
AP Physics C: Electricity and Magnetism · Question 4
AP Physics C: Electricity and Magnetism · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- routine
- Marks
- 1
- Topics
- 1
- Answer
- Complete
multiple choice1 mark
A long solenoid has n turns per unit length and carries a current I. Using Ampère's law, what is the magnitude of the magnetic field well inside the solenoid, far from its ends?
- A
μ₀I/(2πr)
- B
μ₀nI
- C
μ₀nI/2
- D
μ₀I/(2R)
Ready to self-mark?Reveal the detailed answer guide
Answer overviewCorrect answer: B — μ₀nI
01
1 markAnswer and reasoning
How to approach it
Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.
- 1
The correct choice is B: μ₀nI
- 2
A is the field of a long straight wire and D that at the centre of a single loop. C is the field at the very end of a solenoid, which is a genuinely different situation from the one described.
Private on this device