Answer: Radio waves (RF pulses, ~64 MHz for 1.5 T MRI).
- A Radio waves (RF pulses, ~64 MHz for 1.5 T MRI)
- B X-rays generated by a high-voltage electron tube
- C Gamma rays emitted from a radioactive tracer isotope
- D Microwaves used for dielectric heating of tissue
Correct answer: A. Radio waves (RF pulses, ~64 MHz for 1.5 T MRI)
Explanation: MRI uses radio frequency pulses that match the Larmor precession frequency of hydrogen nuclei in the magnetic field. At 1.5 T, this is about 64 MHz (FM radio range). MRI is non-ionizing and safer than X-rays.
In an electromagnetic wave, the oscillating electric field (E) and magnetic field (B) are perpendicular to each other and to the direction the wave travels - a purely transverse wave that needs no medium, unlike sound.
Concept context
Maxwell's equations, EM spectrum, properties, and applications of each band.