Radioactivity Definition and 113 Threads

Homework Statement The mean life of a certain radioactive element is 6 hrs. By what fraction will its initial activity decrease over a time period of 5 hrs. Homework Equations t_{avg}=\frac{1}{k} Initial Activity = kN_{0} Final Activity = kN_{t} The Attempt at a Solution From eqn 1...

Can anyone link to a synthetic and understandable explanation of radioactivity through basic quantum mechanics? It does not need to be a comprehensive explanation at all, examples or partial explanations are fine. Online class notes are welcome but so are books suggestions. Thanks in advance

Homework Statement A radioactive substance diminishes at a rate proportional to the amount present (since all atoms have equal probability of disintegrating, ...). If A(t) is the amount at time t, this means that A'(t)= p * A(t) for some p representing the probability that an atom will...

What would be the shape of an "Activity versus Number of Atoms present" graph look like... We know that A=-λN ... They are propotional but there is a negative sign.. What would be the graph?? Thanks in advance!

Homework Statement 0.2g of a radium salt was separated from a ton of uranium ore. The radioactive radium nuclide Ra-226 decays by alpha-particle emission with a half-life of 1600 years. 1 year = 3.16x107s. The curie is defined as the number of disintegrations per second from 1.0g of Ra...

Homework Statement The activity of carbon, due to the decay of C14, is 16 disintegrations per minute per gram of carbon. The atomic weight of naturally occurring carbon is 12 u. What is the ration of C14 to C12 in the CO2 of the atmosphere? The half life of C14 is 5730 years. Homework...

Hi, My Physics textbook talks about a nucleus disintegrating. What does this mean? I understand that the nucleus will emit either an alpha, beta or gamma ray but surely the nucleus still remains after this? Does the term disintegrate just mean than the nucleus has got smaller and become a...

Hello, I am asked to plot the activity of 137Cs in a 1Gw fission reactor over time of 100 years if the reactor is active from 0-20 years and shuts down at 20 years. So here are the facts: The reactor capacity is 1Gw Reactor is active for the first 20 years then shuts down At shutdown...

Is it true that all the Experiments which are intend to prove Time-Dilation of SR 'directly', are based on radioactive half-lives extension ? For example, cesium atomic clocks in GPS satellites, Muon decay etc. Moreover, if it is true, ... and correlations between nuclear decay rates...

I want to know that if one sends a radioactive material in a spaceship at high speed and bring it back, do we find that the radioactive material has decayed slower than it would on Earth or the same rate? As radioactivity doesn't depend on the Coulombic interaction (photons), rather other...

Homework Statement A nuclear power plant breeds 1mg of 239Pu per week. What activity, in Bq, does that create? Homework Equations R_0 = \lambda N_0 (initial activity of the sample) R = R_0 e^{-\lambda t} (exponential behavior of the decay rate) T_{1/2}=\frac{ln 2}{\lambda}...

In the radiactivity equation A = A0e-ln(2)t/T1/2 How do I get A0? Is that just ln(2)N0/T1/2? What if I don't know the initial number of atoms in the sample? Thanks...

cluster radioactivity --- preformed cluster model In cluster radioactivity, heavy nuclei decay to form Helium, Carbon, Nitrogen, Silicon etc. I came across the term Preformed cluster model. What is preformed cluster model? Members, could you please throw some light on this?

Homework Statement Complete this reaction equation: ^9_4 Be + ^1_0 n \rightarrow ^4_2 He + ? Homework Equations Not relevant The Attempt at a Solution I find the answer to be ^6_2 He , but the answer key in my book says ^7_3 Li I can't see how that can be right, please help!

Homework Statement 90% of the cosmic rays that fall on Earth are protons. So the outside of the Earth is hit by a net positive charge but does not seem to be, in particular, positively charged. How do you explain this? One last thing: I read that a body that is exposed to radiation becomes...

Not sure if this is the right forum, please move if a more appropriate forum exists. Even after Fukoshina I'm not quite sure what to make of radioactivity, how to read levels or radiation and what the danger is of getting sick. Below are two small articles about the Aktau area in western...

Most texts on radioactivity starts by saying "there are three important modes of radioactivity-alpha, beta and gamma..." and goes on to describe their properties. But why are there only a few modes of radioactivity? Does that mean the modes observed so far, or, are there theories to describe the...

cluster radioactivity-- want to know more? Dear members, While browsing through some quantum mechanics websites, i came across cluster radioactivity, which surprised me, because so far i didn't hear that term as i am familiar with natural and artificial radioactivity. It has been mentioned...

Fukushima - Unit 2, what happened different to Units 1 and 3? There are recent discussions about this topic going on, so I think it deserves its own thread. According to attachement IV-2, Unit 2 is responsible for more than 90% of the overall emissions. So there's one big question: What was...

1. A cobalt-60 source having a half-life of 5.27 years is calibrated and found to have an activity of 3.50 × 105 Bq. The uncertainty in the calibration is ±2%. Calculate the length of time, in days, after the calibration has been made, for the stated activity of 3.50 × 105 Bq to have a maximum...

Homework Statement A radioactive material decays by simultaneous emission of two particles with respective half-lives t1 and t2. If the material decays by the emission of the particle with half-life t2 only, then the time in year after which 1/4 th of the material remains is. (Given t1=1620...

Radioactivity of Radon 222! Homework Statement Uranium is naturally present in rock and soil. At one step in its series of radioactive decays, Uranium produces the chemically inert gas radon-222, with a half-life of 3.82 days. The radon seeps out of the ground to mix into the atmosphere...

There is a lot of speculation about this. Is that really possible? It is being proposed that after meltdown and release the nuclear material will enter the Jet Stream and be in west Coast US in a few days. Personally I find it hard to swallow. I mean we exploded two nuclear devices over...

Is it possible for a virtual particle consisting of a proton/antiproton pair to "pop" into existence close enough to the nucleus of a helium atom (two protons and two neutrons) such that the antiproton of the virtual particle annihilates one of the protons of the helium atom leaving Tritium (H3)...

Homework Statement A mixture of Pu239 and Pu240 has a specific activity of 6 x 109 dps. The half-lives of the isotopes are 2.44 x 104 years and 6.58 x 103 years respectively. Calculate the composition of the mixture.The Attempt at a Solution The last equation does not give permissible values.

Homework Statement How many radioactive atoms are present in a sample of 6GBq of 99mTc and what is the approximate mass of the sample? Homework Equations A= λN half life = ln2/λ mass = (no.nuclei * mass number)/avorgado number avogado = 6.023×10^23 half life = 6 hours The...

I understand decay is truly a random process approximated by half-life. So two particles that appear similar to us in every way will experience decay at different times impossible for us to predict. Are there any theories that explain some underlying process that dictates this action. Even...

Homework Statement Radioactive iodine (131-I) has a half life of 8 days. How long does it take for iodine to be reduced by factor of 100? Homework Equations N(t)=N(o)e-kt k=ln100/t1/2 The Attempt at a Solution N(t)=N(o)e-kt N(t)/N(o)=e-ln(100/8)t Now I'm stuck. I would...

Homework Statement A piece of Am-241 has a radioactivity of 10kBq. Determine how much Am-241 it contains. Homework Equations N(t)=N_0(\frac{1}{2})^{t/T_{1/2}} The Attempt at a Solution Let A be the activity Let N be the number of atoms We know that...

Okay this question is in a section of my textbook that has no equations, apart from the slightly mathematical statement: The rate at which a source emits radioactive particles is called its activity, A. An activity of one particle emitted per second is called a becquerel, Bq. Here's the...

Homework Statement Thorium (with half-life T1/2 = 1.913 yr. and atomic mass 228.028715 u) undergoes alpha decay and produces radium (atomic mass 224.020186 u) as a daughter nucleus. (Assume the alpha particle has atomic mass 4.002603 u.) (a) What is the decay constant of thorium? (Note that...

A piece of radioactive substance gives a received count rate of 6000 counts per minute in a detector whose efficiency is known to be 5%. If the sample contains 10^10 atoms, what is the decay constant ( λ ) of this radioactive substance ? No idea how to solve this problem. Any help would be...

Hi Guys, Im just having a little trouble with this question, I was just wondering whether some one could point me in the right direction. Fifty six micrograms of 60Co - labeled Vitamin B12 containing 7.36x10^5 c.p.m were added to a sample containing an unknown amount of unlabeled Vitamin...

1.Explain why if a sample has a very short half-life, then it will be more radioactive than an element that has a longer half-life, any clues anyone?

1. when alpha particles are emitted, the atomic number decreases by2, but is the new element charged due to more number of electrons? If not, what happens at the nuclear level? Please, Explain it simillarly about beta particles. 2.when describing the emission of beta particles, we say that...

Hello everybody :) I've been wondering about how radiation is harmful for living beings... I know that the three kinds of radiation (α, β, γ). α radiation composed of helium nuclei (2 protons and 2 neutrons), β radiation is composed by the emission of electrons, caused by the conversion of...

I know that if a radioactive substance is heated, then the radioactivity is reduced because of the relativistic thermal motion of the atoms. Is there a formula linking radioactive decay, temperature and perhaps, heat capacity?

Homework Statement Thorium (with half-life T1/2 = 1.913 yr. and atomic mass 228.028715 u) undergoes alpha decay and produces radium (atomic mass 224.020186 u) as a daughter nucleus. (Assume the alpha particle has atomic mass 4.002603 u.) (a) What is the decay constant of thorium? (Note that...

Homework Statement One kg of human body contains about 0.2% potassium of which 0.0117% is potassium- 40 (40K). 40K is radio active and in 89% of the time the product of the decay is a gamma ray of energy 1.46 MeV. If we assume that all of these gamma rays deposit their energy in the body...

Homework Statement Thorium (with half-life T1/2 = 1.913 yr. and atomic mass 228.028715 u) undergoes alpha decay and produces radium (atomic mass 224.020186 u) as a daughter nucleus. (Assume the alpha particle has atomic mass 4.002603 u.) The energy released from the decay of 0.6 g of...

[SOLVED] Radioactivity and radioactive decay Homework Statement Thorium (with half-life T1/2 = 1.913 yr. and atomic mass 228.028715 u) undergoes alpha decay and produces radium (atomic mass 224.020186 u) as a daughter nucleus. (Assume the alpha particle has atomic mass 4.002603 u.) What...

[SOLVED] Radioactivity -- Why no reading on Geiger counter? Homework Statement A magnet is directly between a Geiger counter and a material that is know to be radioactive. If the Geiger counter does not register any radioactivity, what kinds of particles is the radioactive substance emitting...

NOTE: This is not homework, but if you feel it is in the wrong forum then move it. I didn't know a better forum that it could go in. I want to construct a table of results (minus the results for now) that is related to how the count rate on a geiger muller counter varies with distance with a...

Homework Statement The problem: 4000,000 gal of water remained in a contaminated building at 3 mile island. The principle sources of radioactivity were: 137Cs at 156E-6 Ci/cubic cm and 134Cs at 26E-6 Ci/ccm. How many atoms/ccm were in the water? Homework Equations 137E-6*3.7E10 Ci=...

URGENT HELP Question About Radioactivity Im doing some Coursework in for... tomorow :S I know my own fault! but I've only just come across the Problem and I've been doing it for the last few Days. Im designing an experiment Investigating the effect of Thickness of Aluminium against the Rate of...

1) Methods/equipment for radioactivity detection. For my high-school Chemistry studies, needs clarification. Geiger counter: A small chamber contains a high voltage electric field inside filled with inert gas. When ionizing particles/radiation enters the chamber, it will ionise the...

i have been given an equation of, delta(N) = N(t).delta(t)/T where N(t) is the number of atoms left at time t, and T is the half life. Using a constant time and variable half lifes i have to come up with a formula to calculate the remaining atoms left over. the formula i was able to...

I have 3 questions dealing with radioactivity: Q1. Which particle, alpha or beta, is least massive? A1. well alpha particles are emitted as 4,2 Helium nuclei and beta particles are emitted as either electrons or positrons. So would the beta particles be least massive? Q2: Do all alpha...

What forces are actually involved in radioactivity other than the weak nuclear force? And would anyone know any nice animations that one could view on the net of radioactive decay processes? Thanks

It is necessary to determine the strength of a radioactive source. Counting equipment has been made available for only two hours. How should the time be schedule if: The net source counting rate is 7 times the background rate. I mean I would say that you would use relatively short counting...