No, electromagnetic radiation does not change its wavelength while propagating through a vacuum or a homogeneous medium. The wavelength of electromagnetic radiation remains constant in free space, meaning it does not undergo any changes in a vacuum.
Wavelength is a characteristic property of electromagnetic waves, and it is determined by the source of the radiation or the frequency of the wave. Different sources or frequencies will emit electromagnetic waves with different wavelengths.
However, when electromagnetic radiation encounters a medium with different optical properties, such as a transparent material, its speed changes. This change in speed can result in a change in the wavelength of the radiation, while the frequency remains constant. This phenomenon is known as wavelength dispersion.
When electromagnetic radiation passes from one medium to another (e.g., from air to water or from air to glass), it can experience refraction, where the change in speed causes the wave to bend and the wavelength to change. This change in wavelength is related to the change in the speed of light in the new medium according to Snell's law.
It's important to note that while the wavelength may change in a medium, the frequency of the electromagnetic radiation remains constant. The frequency determines the color or energy of the light, while the wavelength determines its spatial characteristics.