Final answer:
Radio waves have a longer wavelength and smaller frequency compared to visible light. The correct answer is option 3, which fits with the overall principles of the electromagnetic spectrum and the inverse relationship between frequency and wavelength. Therefore, the correct option is 3.
Step-by-step explanation:
Radio waves have longer wavelength and smaller frequency relative to visible light. Therefore, the correct answer to the question is option 3) longer; smaller. This relation is part of the fundamental principles of the electromagnetic spectrum, where waves like radio waves, which are at one end of the spectrum, have longer wavelengths and smaller frequencies compared to waves like visible light, which are located closer to the middle of the spectrum.
Furthermore, according to the relationship between frequency and wavelength in electromagnetic waves, when frequency increases, wavelength decreases, and vice versa, given that the speed of light is a constant in a vacuum. Also, it's important to understand that the energy of a wave is related to its frequency: higher frequency waves have more energy. Thus, radio waves have less energy compared to visible light due to their lower frequencies.