Which electromagnetic wave has the longest wavelength?

Which electromagnetic wave has the longest wavelength?

• A. Gamma ray
• B. Radio wave
• C. Infrared
• D. Ultraviolet

Answer: (B)

Wavelength and frequency are inversely related for electromagnetic waves: they all travel at the same speed, so a longer wavelength means a lower frequency (λ = c/f). Among the options, radio waves have the longest wavelengths, spanning from millimeters up to thousands of kilometers. Infrared, ultraviolet, and gamma rays all have much shorter wavelengths (infrared in the micrometer to millimeter range, ultraviolet in the nanometer range, and gamma rays even shorter). So the radio wave is the one with the longest wavelength.

Wavelength and frequency are inversely related for electromagnetic waves: they all travel at the same speed, so a longer wavelength means a lower frequency (λ = c/f). Among the options, radio waves have the longest wavelengths, spanning from millimeters up to thousands of kilometers. Infrared, ultraviolet, and gamma rays all have much shorter wavelengths (infrared in the micrometer to millimeter range, ultraviolet in the nanometer range, and gamma rays even shorter). So the radio wave is the one with the longest wavelength.