Question

Which of the following types of electromagnetic radiation has the shortest frequency?

Infrared waves

Microwaves

Ultraviolet waves

X-rays

Answer 1

micro wave

Answer 2

Are you asking about wavelength (which can be long or short) or frequency? Frequency is high or low. The smallest frequency (and longest wavelength) would be infrared - the others have higher frequency (the energy is proportional to the frequency by the way).

There's a good page about the EM spectrum: http://en.wikipedia.org/wiki/Electromagnetic_radiation