There are two types of waves: mechanical and electromagnetic. Microwaves, infrared waves, and radio waves are examples of electromagnetic waves. Which claim is TRUE about
the speed of electromagnetic waves?
A: They are not affected by changes in medium.
B: It is slower in a vacuum than in a medium.
C: In a vacuum, its speed equals half the speed of light.
D: It slows down when it goes from a vacuum to a medium.