Question

Consider a radioactive sample with a half-life of one week. How much of the original sample will be left at the end of the second week? The third week? The fourth week?
@Abhisar

Answer 1

Hello @beccamarx19 !

Answer 2

Half-life (t\(\huge_½\)) is the amount of time required for a quantity to fall to half its value as measured at the beginning of the time period.

Answer 3

If number of half lives elapsed is n, then fraction of radioactive sample remaining will be \(\huge\frac{1}{2^n}\)

Answer 4

For instance, if some radioactive substance has a half life of 5 days then after 30 days i.e 6 (n=6 here) half lives \(\huge\frac{1}{2^6}\) i.e \(\huge\frac{1}{64}\) of the original sample will remain

Answer 5

Can u calculate the answer for ur original question ?

Answer 6

how did you get that?

Answer 7

3.5, 24.5, 10.5?

Answer 8

In ur question half life is given 1week now for two weeks n=2
Amount left will be \(\huge\frac{1}{2^2}\) = .025 or 25% of the original sample

Answer 9

Can u calculate for 3rd week ?

Answer 10

???

Answer 11

i got 10.5

Answer 12

3.5,7,10.5

Answer 13

For 3rd week n will be equal to 3, so amount left = \(\huge\frac{1}{2^3}\) = 0.125 = 12.5%

Answer 14

i thought it was times the days?

Answer 15

For 4th week n will be equal to 4, so amount left = \(\huge\frac{1}{2^4}\) = 0.062 = 6.2%

Answer 16

Times the days was in my example because half life was 5 days, in ur question half life is one week

Answer 17

hold up

Answer 18

ok

Answer 19

ok so it is

Answer 20

\[1/2^{1}\]

Answer 21

\[1/2^{2}\] \[1/2^{3}\] ?

Answer 22

0.5,1,1.5?

Answer 23

0.5 for 1 week, 0.25 for two weeks, 0.125 for three weeks

Answer 24

\(\huge\frac{1}{2^2}\) = \(\huge\frac{1}{4}\)

Answer 25

right

Answer 26

got it ?
u were doing calculationmistake

Answer 27

and half of 1/4 is 1/8

Answer 28

GOT IT!!!