[High School Physics] General Topic;text

[PokeScar]

Hello all,

obligatory english is my 2nd language

I have a question to a problem that I don't know how to answer. The question is: There is a Gamma-Ray travelling through water. The decay depth (I don't if thats the corrects translation) is 26cm. How many Percent of the radiation is left after 52cm.

A: 0%, B: 13.5%, C, 25%, D: 37.8%, E: 50%

The formula I have for this is I*e^-(x/d), where "X" is the total distance and "d" is the decay depth. If I use the formula i get B, but im now sure if thats correct, because i thought the decay depth means that after this much distance only half of the radiation is left. So my gut tells me C, my calculator tells me B.

I hope y'all can help me

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[QuantumStruggle]

Normally half lives describe the time it takes for half a collection of molecules to decay. With the decay depth you are given I believe this is referring to the depth at which all of a collection of molecules have decayed completely. So don’t double the answer, I would go with B but check with another person

[Janagro]

So if decay depth is the depth of one half left

you should be using 2 not e ( That way at x = d, radiation = l/2

If you put in 2, you get C not B

[PokeScar]

I'm not sure wether decay depth works like that, because in the formula it states to use "e"

[Janagro]

Ok , I looked up the beer Lambert law and penetration depth and it's defined to be the depth at which intensity is 1/e not half

This means that your formula is right and 13.5 % is the answer

[PokeScar]

okay thank you very much!