C 1 19. All waves transfer energy through an oscillating medium. Electromagnetic waves are produced by the oscillations of A. electric fields only B. magnetic fields only C electric and magnetic fields D. electric, magnetic, and gravitational fields O Use the following list of types of electromagnetic radiation to answer questions 20 to 22. infrared 2 ultraviolet 3 gamma ray 4 radio 5 X-ray 6 microwave 20. The forms of electromagnetic radiation with wavelengths longer than that of visible light listed from highest to lowest energy are a, b, and c. Which numbers in the given list correspond to a, b, and c? 21. The forms of electromagnetic radiation with photon energy more than that of visible light arranged from lowest to highest energy are a, b, and c. Which numbers in the given list correspond to a, b, and c? 4, 6, 1