Which of these is constant for all types of electromagnetic radiation in a vacuum? select one: a. wavelength b. frequency c. photon energy d. amplitude e. velocity

electromagnetic radiations are of various energy range

this energy of electromagnetic waves will depend upon its frequency as well as wavelength

so we will have

or we can say

so here we can say that all electromagnetic waves must have different energy due to which wavelength and frequency must be different

now we also know that intensity depends on energy and it directly proportional to amplitude of wave

so for different electromagnetic radiation we will have different amplitudes

but we also know that speed of electromagnetic waves will change on changing the medium of wave

so here velocity of wave will remain same for all range in vacuum

so correct answer will be

E. velocity