What is the primary characteristic of gamma rays?

Gamma rays are high-energy electromagnetic radiation that possess a significant ability to penetrate various materials. This characteristic is primarily due to their very short wavelengths and high frequencies, which allow them to pass through substances that would block lower-energy forms of radiation, such as alpha or beta particles.

Gamma rays can travel through several centimeters of lead or several meters of concrete, making them particularly dangerous in terms of radiation exposure, as they can penetrate human tissue and cause cellular damage. This penetrating power is a key factor in various applications, including medical imaging and cancer treatment, where gamma rays are utilized for their ability to target tumors while being able to travel through surrounding healthy tissue.

The other options present characteristics that do not apply to gamma rays. They are not low energy as they are among the highest energy forms of electromagnetic radiation. Gamma rays are not visible to the naked eye, as they fall outside the visible spectrum, and they travel at the speed of light, which is much faster than sound. This combination of properties makes gamma rays distinctive and critical to understand in the context of physics and radiation safety.