All parts of the electromagnetic spectrum travel at a speed of 3 × 108 m/s when traveling through no medium. A "vacuum” means that there is no medium, such as a tube without any air in it. Therefore, 3 × 108 m/s is said to be the speed of light in a vacuum.
Answer
A
Wavelength doubles and speed doubles.
B
Wavelength doubles and speed stays the same.
C
Wavelength divides in half and speed doubles.
D
Wavelength divides in half and speed stays the same.