Yes, it is true that X-rays have a higher velocity than microwaves. The velocity of electromagnetic waves, including X-rays and microwaves, is determined by the properties of the medium through which they travel. In a vacuum, all electromagnetic waves travel at the same speed, which is approximately 299,792,458 meters per second (denoted as the speed of light, often rounded to 3 x 10^8 m/s).
However, when electromagnetic waves pass through a medium other than a vacuum, their velocities can be affected. The speed of light in a medium is given by the equation v = c/n, where v is the velocity of light in the medium, c is the speed of light in a vacuum, and n is the refractive index of the medium.
The refractive index is a measure of how much a medium slows down the speed of light compared to its speed in a vacuum. Different materials have different refractive indices, and this property determines the velocity of electromagnetic waves in those materials.
X-rays have a higher velocity than microwaves because they have a shorter wavelength and higher frequency. X-rays have a much higher energy and can penetrate materials more effectively. Due to their higher energy and shorter wavelength, X-rays are less affected by the refractive index of a material compared to microwaves, which have longer wavelengths.
In summary, the velocity of X-rays is generally higher than that of microwaves due to the differences in their energy, frequency, and wavelength.