Telescope classification by electromagnetic wavelength

Steps:

• Identify the given wavelength: 2 cm (0.02 m).
• Recall electromagnetic spectrum ranges: microwaves (1 mm–1 m), radio waves (>1 m), optical (400–700 nm), X-rays (<10 nm).
• Compare: 2 cm falls within microwave range (1 mm–1 m).
• Conclude: Matches microwave telescope.

Why A is correct:

• Microwaves span 1 mm to 1 m wavelengths per standard EM spectrum definitions, and 2 cm is within this interval.

Why the others are wrong:

• B: Optical telescopes detect visible light (0.4–0.7 μm), far shorter than 2 cm.
• C: Radio telescopes target longer wavelengths (>1 m), outside the specific microwave band.
• D: X-ray telescopes detect very short wavelengths (<10 nm), much smaller than 2 cm.

Final answer: A