The half-life of carbon-14, which is used in dating archaeological finds, is 5730 yr. Assume that 100% of the carbon-14 is present at time 0 yr, or x=0. Write the equation that expresses the percentage of carbon-14 remaining as a function of time.
Amount left = (1/2)^(x/5730)
check:
if x = 0 , amount left = (1/2)^0 = 1 = 100%
if x = 5730 , amount left = (1/2)^(1) = 1/2 = 50%
formula is good!
Thanks so much!
Could you tell me the base formula used for that?
normally I would have used \
amount = a(e^(kt)) where a is the initial amount, in your case it was 1 for 100%
and k is some constant.
but since they were talking about "half-life" I used 1/2 as the base
for half-life questions,
amount = a(1/2)^(t/half-life period)
in your case
amount = 1(1/2)^(t/5730)
To express the percentage of carbon-14 remaining as a function of time, we can use an exponential decay model.
The formula for exponential decay is:
N(t) = N₀ * (1/2)^(t/h)
Where:
- N(t) represents the amount of the substance remaining at time t.
- N₀ represents the initial amount of the substance (at time t=0).
- t represents the time elapsed.
- h represents the half-life of the substance.
In this case, we want the percentage of carbon-14 remaining, so we divide N(t) by N₀ and multiply by 100 to get the percentage.
Therefore, the equation that expresses the percentage of carbon-14 remaining as a function of time is:
P(t) = (N(t) / N₀) * 100 = (1/2)^(t/h) * 100
Where:
- P(t) represents the percentage of carbon-14 remaining at time t.
- t represents the time elapsed.
- h represents the half-life of carbon-14, which is 5730 years in this case.