Following are the wavelength of some constituents of the electromagnetic spectrum. The wavelength range that are used in Radar system for Aircraft navigation is:
(A) 1 mm to 700 nm
(B) 0.1 m to 1 mm
(C) 400 nm to 1 nm
(D) \( \lt 10^{-3} \) nm
(E) \( \gt 1 \) m
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (B) only
Radar systems for aircraft navigation use microwaves: their short wavelength lets them be sent out as a narrow beam and reflected well from aircraft. Each listed range belongs to one band of the electromagnetic spectrum.
(A) 1 mm to 700 nm — Incorrect. This is the infrared band, used in remote controls and for heating, not in radar.
(B) 0.1 m to 1 mm — Correct. This is the microwave band, the one used in radar for aircraft navigation.
(C) 400 nm to 1 nm — Incorrect. This is the ultraviolet band, used in water purifiers and LASIK eye surgery.
(D) \( \lt 10^{-3} \) nm — Incorrect. These are gamma rays, given out by nuclei and used in medicine to destroy cancer cells.
(E) \( \gt 1 \) m — Incorrect. These wavelengths lie in the radio wave band (above 0.1 m), used for radio and television broadcasting.
NCERT (2026-27):
Microwaves – “Microwaves (short-wavelength radio waves), with frequencies in the gigahertz (GHz) range, are produced by special vacuum tubes (called klystrons, magnetrons and Gunn diodes). Due to their short wavelengths, they are suitable for the radar systems used in aircraft navigation.”