Properties of Electromagnetic Radiation

Steps:

• Identify infrared as part of the electromagnetic spectrum, like visible light and UV.
• Recall that all electromagnetic waves travel at the speed of light in vacuum (3 × 10^8 m/s).
• Evaluate options: check for ionization (requires high energy), wave type (transverse for EM), and frequency order (IR lower than UV).
• Confirm D matches the universal property of EM waves.

Why D is correct:

• Electromagnetic radiation, including infrared, propagates as waves at the speed of light, c = 3 × 10^8 m/s, per Maxwell's equations.

Why the others are wrong:

• A: Infrared lacks sufficient energy for ionization; only high-frequency radiation like gamma rays does.
• B: Electromagnetic waves are transverse, not longitudinal like sound waves.
• C: Infrared has lower frequency (longer wavelength) than ultraviolet in the spectrum.

Final answer: D