Carbon-14 Decay: Dose We Receive from Natural Radiation

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In summary: How many grams of carbon are there in a 76.0 kg person?There are 7.6 grams of carbon in a 76.0 kg person.
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stephaniek
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The radiocarbon in our bodies is one of the naturally occurring sources of radiation. Let's see how large a dose we receive. 14C decays via B- emission, and 18.0% of our body's mass is carbon.

a) Write out the decay scheme of carbon-14 and show the end product. (A neutrino is also produced.)
answer: 146C ------> e- + 147N + ve

b) Neglecting the effects of the neutrino, how much kinetic energy (in MeV ) is released per decay? The atomic mass of C-14 is 14.003242 u.
No idea where to begin tried using E = mc2 did not get the right answer.

c) How many grams of carbon are there in a 76.0 kg person?
no idea how to do this.

d) How many decays per second does this carbon produce? (Hint: Assume activity of C-14 is about 0.255 Bq per gram of carbon.)
No idea about this one either.

Any help would be greatly appreciated.
 
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  • #2
How many grams of carbon are there in a 76.0 kg person?
no idea how to do this.

Carbon is 18.0% of body mass. 76.0 times 18.0%.

How many decays per second does this carbon produce? (Hint: Assume activity of C-14 is about 0.255 Bq per gram of carbon.)
No idea about this one either.

Look up the definition of Bq (Becquerel) in Wikipedia.
 
  • #3
It seems that it is a problem allowing you to use tables. Obviously to use E=mc2 (how do you pretend use it, anyway?) you need the mass difference between carbon and nitrogen. The data of the atomic mass of C-14 is in part a need and in part a red herring (so naive people will try to apply E=mc2 to it, instead asking the tables for the atomic mass of N-14 too).

stephaniek said:
The radiocarbon in our bodies is one of the naturally occurring sources of radiation. Let's see how large a dose we receive. 14C decays via B- emission, and 18.0% of our body's mass is carbon.

a) Write out the decay scheme of carbon-14 and show the end product. (A neutrino is also produced.)
answer: 146C ------> e- + 147N + ve

b) Neglecting the effects of the neutrino, how much kinetic energy (in MeV ) is released per decay? The atomic mass of C-14 is 14.003242 u.
No idea where to begin tried using E = mc2 did not get the right answer.
 

Related to Carbon-14 Decay: Dose We Receive from Natural Radiation

1. What is carbon-14 decay and how does it affect us?

Carbon-14 decay is the process by which the radioactive isotope carbon-14 breaks down into stable elements over time. This process occurs naturally in the environment and affects us through exposure to radiation.

2. How is carbon-14 decay measured?

Carbon-14 decay is measured through the half-life of the isotope, which is the amount of time it takes for half of the original amount to decay. The half-life of carbon-14 is approximately 5,730 years.

3. What is the source of carbon-14 in our bodies?

The primary source of carbon-14 in our bodies is through the food we eat. Plants absorb carbon-14 from the atmosphere through photosynthesis, and animals consume these plants, passing on the carbon-14 to us through the food chain.

4. How much radiation do we receive from carbon-14 decay?

The amount of radiation we receive from carbon-14 decay is relatively low. On average, we receive about 0.0002 mSv (millisieverts) per year from carbon-14 in our bodies, which is a small fraction of the annual background radiation we are exposed to from various sources.

5. What are the potential health effects of exposure to carbon-14 radiation?

The low levels of radiation from carbon-14 decay are not harmful to our health. However, exposure to high levels of radiation can increase the risk of cancer and other health effects. It is important to limit exposure to all sources of radiation, including carbon-14, to maintain overall health and well-being.

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