Which of the following waves has the highest frequency?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Cosmic waves
The frequency of a wave is the number of vibrations it makes per second; for radiation, the higher the frequency, the shorter the wavelength and the greater the energy. Cosmic radiation, which reaches the Earth from outer space, carries the highest energies known; its gamma rays are far more energetic than those from any source on Earth, so cosmic waves have by far the highest frequency of the four.
Why the other options are incorrect
Option (1) Supersonic waves — Incorrect. ‘Supersonic’ refers to a speed greater than that of sound; sound waves have low frequencies, from about 20 Hz up to the ultrasonic range.
Option (3) Radio waves — Incorrect. They have the lowest frequencies and longest wavelengths of the electromagnetic spectrum.
Option (4) Microwaves — Incorrect. They lie just above radio waves in frequency (about 1 to 300 GHz), far below cosmic rays.