Carbon 14 dating 1 | Life on earth and in the universe | Cosmology & Astronomy | Khan Academy

TL;DR

Carbon-14 is formed in the atmosphere and absorbed by all living things, and its decay rate can be used to determine the age of organic materials.

Transcript

What I want to do in this video is kind of introduce you to the idea of, one, how carbon-14 comes about, and how it gets into all living things. And then either later in this video or in future videos we'll talk about how it's actually used to date things, how we use it actually figure out that that bone is 12,000 years old, or that person died 18,... Read More

Key Insights

• 🙌 Carbon-14 is formed in the atmosphere through cosmic rays interacting with nitrogen-14.
• 🫒 Living organisms constantly take in carbon-14, which becomes part of their tissue.
• ☠️ Once an organism dies, it no longer takes in carbon-14, and the remaining amount decays at a predictable rate.
• ☠️ The decay rate of carbon-14 can be used to estimate the age of organic materials, such as bones or wood.
• 🧑‍🤝‍🧑 Carbon-14 dating is based on the principle of comparing the amount of carbon-14 in a sample to the expected amount in living organisms.
• 🥳 By measuring the ratio of carbon-14 to carbon-12 in a sample, scientists can determine how long ago it died.
• 🧑‍🤝‍🧑 Carbon-14 dating is most effective for samples up to 50,000 years old, as the amount of carbon-14 becomes too low to measure accurately after that time.

Questions & Answers

Q: How is carbon-14 formed in the atmosphere?

Carbon-14 is formed through cosmic rays from the sun, which interact with nitrogen-14 and create neutrons that replace a proton, turning nitrogen-14 into carbon-14.

Q: How does carbon-14 get absorbed by living things?

Carbon-14 combines with oxygen to form carbon dioxide, which is then taken up by plants during photosynthesis. Animals and humans acquire carbon-14 by consuming plants or other organisms.

Q: How can carbon-14 be used to determine the age of organic materials?

Carbon-14 undergoes radioactive decay at a specific rate, known as its half-life. By comparing the amount of carbon-14 in a sample to the expected amount in living organisms, scientists can calculate how long ago the sample died.

Q: What is the half-life of carbon-14?

The half-life of carbon-14 is approximately 5,730 years. This means that after 5,730 years, half of the carbon-14 in a sample will have decayed into nitrogen-14.

Summary & Key Takeaways

• Carbon-14 is formed in the atmosphere through cosmic rays and combines with oxygen to create carbon dioxide, which is absorbed by plants and animals.

• Carbon-14 constantly decays at a specific rate, known as its half-life, and can be used to estimate the age of organic materials.

• By comparing the amount of carbon-14 in a sample to the expected amount in living organisms, scientists can determine how long ago the sample died.