How are x-rays described in terms of their physical properties?

X-rays are a form of electromagnetic radiation that possess unique physical properties. One of the key characteristics of x-rays is that they are invisible to the human eye; this means they cannot be seen, which is essential for their application in medical imaging. Additionally, x-rays travel in straight lines, allowing them to penetrate various materials, including human tissue, and create detailed images on radiographic film or digital sensors. This ability to travel in straight lines is critical for the accurate representation of the internal structures of the body during diagnostic imaging.

The other descriptions do not accurately reflect the nature of x-rays. For example, describing x-rays as visible, lightweight, heavy, or charged does not align with their actual physical properties. Instead, their invisibility and behavior of traveling in straight lines underlie their effectiveness in radiology and imaging practices.