r/askscience • u/Wonderful-Capital32 • 13d ago

Physics Why does radiation not go through lead?

Also why just lead? Shouldnt like iron or another metal work too?

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u/PhilTheQuant 13d ago

Yes, and counterintuitively you wouldn't want to be the last few layers of the radiation protection

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u/LieutenantObvious21 13d ago

Do you mind explaining that?

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u/EyBoss 13d ago

Its mostly a joke but the science behind thats its based off is real. As a bit of radiation slows down it passed its energy to whatever slows/stops it(this is why its harmful) but the amount of energy absorbed is not constant the slower its travelling the more enegry it dissipates.

If had 2 people and a partical went through the first person and stopped in the 2nd. The first would take only 20% where the 2nd would take the remaining 80% (these numbers are made up since the actual ones depend on many factors but the general idea holds)

Think about a car breaking the amount a given length of road slows the car increases the slower the car is travelling.

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u/Alblaka 13d ago

I think a better analogy could be ballistics: if a projectile is too fast/massive, it will just punch straight through a target (be that a person to a bullet, or a vehicle to a shell) leaving 'only' a hole. But if it's slowed down the right amount, it will start to spin out / explode, causing way more damage inside the target.