Why do bones show up on x rays and not skin?

X-rays are a form of electromagnetic radiation, just like visible light, but with much shorter wavelengths. This means that they can pass through many materials that visible light cannot, including skin and muscle. However, dense materials like bone absorb X-rays, which is why bones show up on X-rays as white areas.

The amount of X-rays that are absorbed by a material depends on its density. The denser the material, the more X-rays it will absorb. This is why bones, which are very dense, appear white on X-rays, while skin and muscle, which are less dense, appear gray.

When an X-ray image is taken, a beam of X-rays is passed through the body. The X-rays that are not absorbed by the body pass through to a detector, which converts them into an image. The areas of the image that correspond to dense materials, such as bones, will appear white on the image.