Physics · Dawn of Modern Physics
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Which of the following will be a better shield against 𝛾-rays?
- A
Ordinary water
- B
Heavy water
- C
Lead
- D
Aluminum
Gamma rays are known to have maximum penetration they can penetrate several metals. The best shielding against them is elements with high atomic numbers and high density, such as lead. The atomic number of Lead is 82.
Gamma rays travel at the speed of light, and they can travel thousands of meters in the air before spending their energy. They can be shielded by water but a huge amount would be required: 13.8 feet of water, about 6.6 feet of concrete, or about 1.3 feet of Lead is required to shield against gamma rays. Aluminium is less dense and gamma rays can penetrate through them completely.
This option is incorrect. While water can attenuate gamma rays, a very large thickness is required to provide effective shielding.
This option is incorrect. Although heavy water has a slightly higher density than ordinary water, it is still not as effective as lead in shielding gamma rays.
This option is correct. Lead is an excellent shield against gamma rays due to its high density and atomic number, which effectively absorb the radiation.
This option is incorrect. Aluminum has a lower density compared to Lead, making it less effective in shielding against gamma rays.
Tagged under Physics · Dawn of Modern Physics · 2018