Answer: A charged particle moves faster than light in that medium.
- A A charged particle moves faster than light in that medium
- B An atom undergoes ordinary radioactive nuclear decay
- C Two photons collide and annihilate each other directly
- D A charged particle decelerates suddenly, as in X-ray production
Correct answer: A. A charged particle moves faster than light in that medium
Explanation: Cherenkov radiation is emitted when a charged particle travels faster than the phase velocity of light in that medium (c/n). It appears as a blue glow in nuclear reactors (water acts as the medium).
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.