Answer:
Longer wavelength
Explanation:
The spectrum in which the wavelength or frequency are arranged in increasing or decreasing order is called electromagnetic spectrum. The frequency of gamma rays is maximum while the frequency of radio wave is least.
We know that the frequency and wavelength are inversely proportional to each other.
So, an electromagnetic wave that has a lower frequency than infrared radiation will have longer wavelength. Also the energy of wave is given by :
E = hυ, where υ is frequency of the wave
Hence, the correct option is (a) " longer wavelength ".
