The importance of the half-life is many people not very clear!
The half-time is the time that is necessary to be an exponentially declining value has halved. For radioactive substances, 50% of the nuclei have converted to another Nukleid under secretion of radiation, which in turn can be radioactive.
- An example from the animal world could be the extinction of a species, with no intervening action. Assume that the animal was a tiger or an elephant. Tigers have a very valuable fur, elephant ivory tusks that are highly sought after.
- At the beginning, very few poachers hunt and hunt animals. You can sell the pelts or tusks for a lot of money in the market. This attracts more hunters who see how easy and fast casual earning money.
- This process is repeated, the number of hunters will continue to rise and the stock of animals will be reduced still further. Eventually, the time is reached at which only half of the original animals alive. The time that has elapsed till then, the half-life.
In reality, of course, measures are taken to protect these endangered species.
Another example for the half-life
Example 2: A particularly interesting and important is the half-life of radioactive substances released into the reactor accidents at Chernobyl or Fukushima.
- Many are not aware that such substances have half-lives of several decades. The explosion at Chernobyl activity of several trillion becquerels released. The soil, the atmosphere and the biomass in this region will therefore be contaminated for centuries. Homes and entire regions are no longer be habitable for a long time.
- In particular, the radioactive cesium-137 has a half-life of about 30 years.
- For radioactive decays one can only speak of a probability for the conversion of a core in a unit time. In this context, one also speaks of a decay constant.
Do not forget to radioactive decays: The half-life is reached after several decades, although, because of the large initial emissions of radioactive substances to the environment is still heavily infested!