Electromagnetic radiation is more common than you think. Radio and TV stations emit radio waves when they broadcast their programs; microwaves cook your food in a microwave oven; dentists use X rays to check your teeth. Even though they have different names and different applications, these types of radiation are really all the same thing: electromagnetic (EM) waves, that is, energy that travels in the form of oscillating electric and magnetic fields. Consider the following:
radio waves emitted by a weather radar system to detect rain drops and ice crystals in the atmosphere to study weather patterns;
microwaves used in communication satellite transmissions;
infrared waves that are perceived as heat when you turn on aburner on an electric stove;
the multicolor light in a rainbow;
the ultraviolet solar radiation that reaches the surface of the earth and causes un-protected skin to burn; and X rays used in medicine for diagnostic imaging.
Which of the following statements correctly describe the various forms of EM radiation listed above?
A. They have different wavelengths.
B. They have different frequencies.
C. They propagate at different speeds through a vacuum depending on their frequency.
D. They propagate at different speeds through non-vacuum media depending on both their frequency and the materialin which they travel.
E. They require different media to propagate.