Which statement correctly describes penetrating x-rays?

• A. The most penetrating x-rays travel in short wavelengths
• B. The most penetrating x-rays travel in long wavelengths
• C. Penetration is not affected by wavelength
• D. Penetration is greatest at intermediate wavelengths

Answer: (A)

Penetrating power increases with photon energy. Since energy is inversely related to wavelength (E = hc/λ), shorter wavelengths carry more energy and pass through tissues more readily. That makes the most penetrating x-rays the ones with short wavelengths. Longer wavelengths have less energy and are absorbed or scattered more easily, and intermediate wavelengths don’t maximize penetration. So the statement that the most penetrating x-rays travel in short wavelengths is correct.