Answer: Frequency remains same; wavelength and speed decrease.
- A Frequency remains same; wavelength and speed decrease
- B Speed stays same; frequency and wavelength change
- C All three change
- D Only frequency changes
Correct answer: A. Frequency remains same; wavelength and speed decrease
Explanation: When an EM wave enters a medium, its speed decreases (v = c/n), and wavelength decreases (λ' = λ/n), but the frequency remains unchanged (f = c/λ = v/λ').
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.