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What is the meaning of half life?
The term half-life refers to the period in which the radioactivity or number of atoms of a radioactive substance decreases by half. The term can be applied to any substance whose quantity decreases exponentially with time.
How do you get half-life from a graph?
You can get half-life from a graph by picking two points where the (radio)activity decays to one half its value. The interval of time of those two points is the half-life. You can confirm by picking more points, again with a half (radio)activity value and see that the time is the same in each case.
What is the relationship between half life and radio activity?
Half life is quite simply the time required for a radioactive element to decrease by decay to half the amount.
How do you define half-life in pharmacology?
The term half-life refers to the period in which the radioactivity or number of atoms of a radioactive substance decreases by half. The term can be applied to any substance whose quantity decreases exponentially with time.
As a sample of a radioactive element decays its half-life?
The half-life of a radioactive element is the time it takes for half of the atoms in a sample to decay. As the sample decays, the number of radioactive atoms decreases while the number of stable atoms increases. The process continues in this manner, with each half-life reducing the amount of radioactive material by half.
Can the half life of a radioactive isotope decrease as the isotope decays?
No, the half-life of a radioactive isotope is a constant property of that particular isotope and does not change as it decays. The half-life is defined as the time it takes for half of the atoms in a sample to decay. Once set, the half-life remains constant regardless of how many atoms have decayed.
What is the relationship between half-life and the activity of the scource?
In general, the shorter the half-life of a radioactive substance, the more active it is. Think about it. Say you have two samples of radioactive material the size of sugar cubes. And let's say they have about the same number of atoms of the radioactive substance in them initially, but the substances are different. Substance A has a very short half-life. Substance B has an extremely long half-life. Let's look at what happens. In substance A, the material with the short half-life, atoms will be disintegrating at a high rate. There will be lots of radiation (with the type being determined by the method of decay), and it will have a high activity. It will be "hot" in the language of the physicist. Substance B will be taking its sweet time decaying. One atom here and one atom there will be decaying, and you could hold it in your hand for a while without doing much damage to yourself. In contrast, substance A would have to be kept in a containment cask to keep people who work around it safe from the radiation. For similar amounts of radioactive material, shorter half-lives mean higher activity. Having read this far, it should be simple and easy to see.
What does it mean when a doctor talks about the half life of a dosage of a medication?
The half-life of the drug is the time taken for the plasma concentration of the drug to reduce to 50% of its original value. Units of half life are hour, minute, or day. The formula for calculation half life of a drug is as follows: Cp is the concentration at time one and Cp/2 is the concentration at time one half-life later:- In( Cp/2) = In Cp - Kel . t1/2 half life of the drug (t 1/2) = 0.693/kel
How do you calculate half lives?
The equation for half-life is ...AT = A0 2 (-T/H)... where A0 is the starting activity, AT is the activity at some time T, and H is the half-life in units of T.There are other versions, but they all work out the same way. Using this version, with 2 as the base instead of e, makes it easier to remember.
What is the half life of an isotope that decays to 50 percent of its original activity on 40.9 hours?
15 days
What percentage of a radioactive species would be found as daughter material after seven half lives?
The equation for half-life is AT = A0 2 (-T / H) where A0 is the starting activity, AT is the activity at some time T, and H is half-life in units of T. As a result, seven half-lives would be 2(-7) or 0.0078125 of the original activity.
How long would it take for plutonium to decay to one eighth of its original activity?
For plutonium (or any other radionuclide) to decay to one eighth of its original activity, it will take 3 half-lives of the material. In one half-life, half is gone. Half will be left. In another half-life, half of the half that was left is gone, and one quarter will be left. In a third half-life, half the one quarter will be left, and that's one eighth of the original. In the case of plutonium, there are a number of isotopes of this highly radioactive stuff. The isotope 239Pu, which is commonly used in nuclear weapons, has a half-life of 2.41 x 104 years. That's 24,100 years. For 239Pu to decay to 1/8 th of its original amount, it will take 3 time the half-life, which is 7.23 x 104 years, or 72,300 years. And yes, that is a long time. A very long time....
