Which of the following statement is TRUE of ultraviolet, visible and infra-red rays?

Physics

JAMB 1988

A. they are all electromagnetic waves with the same wavelength
B. ultra-violet rays have shorter wavelengths than infra-red rays and produce flourescence
C. infrared rays have shorter wavelength than visible light and produce the sensation of heat
D. the wavelenghts increase in the sequence: visible, ultra-violet, infra-red

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Correct Answer: Option B

Explanation

Ultra-violet (UV) rays have shorter wavelengths than infra-red (IR) rays.
This is correct. In the electromagnetic spectrum:
UV → shorter wavelength than visible light
Visible light → in the middle
IR → longer wavelength than visible light

So, UV has a much shorter wavelength than IR.

- UV rays produce fluorescence.
This is also correct. Ultraviolet rays are well-known for causing certain materials (like fluorescent dyes, whitening agents, or minerals) to glow or emit visible light — this is called fluorescence. It's commonly used in black lights, forensic science, etc.

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