Which of the following is an example of dense material used for radiation shielding?

Lead is a prime example of dense material used for radiation shielding due to its high atomic number and density, which make it particularly effective at attenuating gamma rays and X-rays. When radiation encounters a dense material like lead, the probability of interaction with the lead atoms increases significantly, reducing the intensity of radiation that can pass through.

Lead's effectiveness is rooted in its ability to absorb and scatter radiation, which is quantified in terms of its mass attenuation coefficient. The denser the material, the more significant the reduction in radiation exposure, making lead a preferred choice in applications such as radiation therapy rooms, nuclear medicine facilities, and other environments where radiation exposure is a concern.

In contrast, aluminum, wood, and glass do not provide the same level of shielding as lead. Although aluminum is used in some applications due to its lightweight nature and moderate attenuation properties, it is not as effective as lead for high-energy radiation. Wood and glass have even lower densities and atomic numbers, making them less suitable for shielding against penetrating radiation.