Case: Read the passage and answer the following questions

The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation is energy that travels and spreads out as it goes – the visible light that comes from a lamp in your house and the radio waves that come from a radio station are two types of electromagnetic radiation. The other types of EM radiation that make up the electromagnetic spectrum are microwaves, infrared light, ultraviolet rays, X- rays and gamma rays.

What physical quantity is the same for X rays of wavelength 10^-15 m, red light of wavelength 7200 A^o and radiowaves of wavelength 750m?

Speed in vacuum

Generally speaking, we say that light travels in waves, and all electromagnetic radiation travels at the same speed which is about 3x10⁸ m/s through a vacuum.