MCAT® ExamChemical and Physical Foundations of Biological SystemsEasy
A medical physicist is designing a new imaging device that requires a strong, uniform magnetic field. Which of the following configurations would be most suitable for generating such a field?
- ATwo parallel current-carrying wires with current in opposite directions.
- BA flat circular loop of current-carrying wire.
- CA solenoid with many closely spaced turns of current-carrying wire.
- DA single straight current-carrying wire.
Show answer & explanationAnswer & explanation
Correct answer: C. A solenoid with many closely spaced turns of current-carrying wire.
A solenoid, which is a cylindrical coil of wire, produces a nearly uniform and strong magnetic field inside its core when a current passes through it. This characteristic is often exploited in medical imaging devices like MRI machines.
Why the other options are wrong
- A. Two parallel wires create a complex magnetic field pattern, not a uniform field suitable for imaging.
- B. A circular loop produces a stronger field at its center, but it's not uniform throughout a large volume.
- D. A straight wire produces a magnetic field that circles the wire and decreases with distance, not uniform.
Solenoid Magnetic Field
A solenoid is a coil of wire wound into a tightly packed helix. When current flows through it, it generates a nearly uniform and strong magnetic field inside the coil, similar to a bar magnet.
- Magnetic field inside is approximately uniform.
- Field strength depends on current, number of turns per unit length, and permeability of the core.
- Used in electromagnets, MRI machines, and relays.
Memory trick: Solenoid: Super Uniform, Optimal for Imaging Devices.