Radioactive Definition and 391 Threads

Hello I am doing radioactivity with my year 10 class and it has set me think about something. I would be grateful for clarification on the following issue and also any other facts that you would like to share that would be of interest to 14 year olds! My issue: all the famous...

Radioactive Decay Probability? Say you are counting the number of decays and the time of observation is varied. I know that as time increases, the Gaussian Distribution becomes a closer fit to the observed probability than when the time interval takes smaller values because the mean count...

I ask this because I've heard repeatedly that all the equations in current physics models are reversible in time, save the second law of thermodynamics. But does this mean the process of radioactive decay is also reversible in time?

My question has a few sub-questions. How long does an area stay contaminated, say after a bomb? A reactor leak? Would different radioactive materials leave an area contaminated longer than others? What would be the most scientifically plausible for an author to explain the 1000-year...

I would like to hear opinions on the variation in decay rates as described by Fischbach and coworkers and how (if at all) this will affect radioemtric dating. Does this phenomenon indeed exist or is it the result of errors in experimental technique?

What are the thoughts about using a magnetic sail propelled by a powerful alpha emitter (e.g. polonium)? Imagine a 1kg sphere of polonium radiating alpha particles in all directions. Attached to the sphere, via boon, is a powerful magnetic field emitter that would repulse or even deflect forward...

Homework Statement The radioactive decay of a substance is proportional to the present amount of substance at any time t. If there was 15 grams at t=0 hours and 10 grams at t=3 hours. Set up the differential equation that models this decay and use the method of separation of variables to solve...

Homework Statement Radioactive decay is: N = N0e-λt N can also be used to describe count rate after a time, (t) where N0 is intial count rate and λ is decay constant... Half life, t1/2 od radioactive isotope is t1/2 = 1n2 λ The λ should be under the ln2 but it won't let...

Hi, This might be a silly question but I've been struggling to find this out. What is the relationship between dose rate and the amount of Cs-137 in an area? if I know the exposure dose of the area is 5mSv, how can I work out how much Cs-137 is in this area? Thanks

Hi, does anyone know how I can find out the max. concentration of Cs-137 and Sr-90 in water?

Homework Statement A radioactive sample contains 2.25g of an isotope with a half-life of 3.8 days. How much of the isotope in grams will remain after 11.0 days? Homework Equations The Attempt at a Solution Hi! I've just started college this semester. I'm taking Introductory Chemistry. Right...

Hi! I know that there are several way to capture radioactive particles in water, but does anyone know how to capture the particles in air? I thought above using moisture to trap the particle, but what if temperature is very low hence hard to introduce moisture? Is there any other ways to trap...

Homework Statement The initial amount of radioactive atoms on a sample of 24Na is 10^10. It's half-life corresponds to 15 hours. Give the amount of 24Na atoms that will disintegrate in 1 day.Homework Equations I started to solve it using the formula N=Initial Amount of Atoms /...

I've just been really thrown off by what this problem is asking me. Given: The decay of a radioactive material may be modeled by assuming that the amount A(t) of material present (in grams) at time t (minutes) decays at a rate proportional to the amount present, that is dA/dt= -kA for some...

I've been reading of the (surprising) fact we are uncertain on whether there is Nuclear Fission in the center of the Earth or not (yet we know so much detail on structures at the other end of the Universe), and I wonder, was the Earth radioactive at its early stages? And if yes, would that...

Homework Statement A sample of thorium-226 is stored in a lead box. Thorium-226 undergoes alpha decay. The lead box has a small opening on the left side to allow a stream of alpha particles to escape. In the sample a nucleus of thorium-226 is at rest when it undergoes alpha decay. The daughter...

Hi, I'm considering the following process n+p→d+\gamma where d is the deuteron and \gamma a photon. I want to find out the energy of the photon. I know it will be much less than the rest mass of the deuteron (1875.666 MeV/c2). Can I simply use conservation of energy here? i.e E\gamma...

Homework Statement A meteor contains 2.45kg of plutonium-239. It has a half-life of 24065 years. Calculate: a) The number of plutonium molecules currently present in the meteor (at. mass = 239.052) b) How long ago the meteor struck the Earth if originally it contained 10kg of plutonium...

Homework Statement 2. A meteor contains 6kg of molybdenum-93. Calculate: a) The number of molybdenum molecules currently present in the meteor. b) How long ago the meteor struck the Earth if the original amount contained 20kg of molybdenum.Homework Equations Answers: 2. a) 3.884x1022...

"Radioactive waste will stay dangerous for hundreds of thousands of years" There's one statement which's always used by people opposed to nuclear power - that the waste will stay dangerous for thousands, ten thousands and even hundred thousands of years. But I'm wondering - is this accurate...

Homework Statement I need to write a program that, given the decay constant of a radioactive material, will calculate numerically (to withing one second) the time taken for half of the orginal sample of material to decay.Homework Equations λ = decay constant C0 = start amount of material...

Homework Statement Suppose that you wish to find out how much gasoline is in an underground storage tank. You pour in one gallon of gasoline that contains some half-life radioactive material that causes a Geiger constant to register 48400 counts per minute above background radiation. The next...

Hello, I am trying to simulate the gammas from certain radioactive decays but I am really puzzle as to how to approach this. The site I'm using as a reference lists the intensities of the different gammas corresponding to an specific decay. The thing that confuses me is that, for example...

Homework Statement After 25 years, 60% of a radioactive material decays. What is the half-life? Homework Equations I used a ratio of 25/.60= x/.50 The Attempt at a Solution I also tried this ratio as 25/.40= x/.50 I am not really sure what equation I should be using but this...

If 40 grams of radioactive substance decomposes to 20 grams in 2 years, then to the nearest gram the amount left after 3 years is well i used the $N(t)=N_{0}e^{-kt}$ So $20=40e^{-k2}$ thus deriving k=.3466 Thus $N(3) = 40e^{-.3466(3)}$ resulting in: $N(3)= 14.1410$ or approx $14g$ just...

Do ions have a measurably different rate then their neutral counterpart or does the rate of radioactive decay and electrons have no correlation? Also, when a source states an elements half life is that the same for all of its isotopes?

Would the observed half-life of a sample of a radioactive isotope (eg. iodine 131) be different from the nominal half-life when it is cooled down to a temperature near absolute zero. Have there been any experiments conducted to examine this question?

Homework Statement The edge of a nucleus can be roughly modeled as a square potential barrier. An alpha particle in an unstable nucleus can be modeled as a particle with a specific energy, bouncing back and forth between these square potential barrier. Consider a nucleus of radius r and an...

I don't have much of a scientific background, but I am interested in learning about geology. More specifically I would like to study the nature of igneous rocks, particularly their formation through volcanic processes. I'm also very much interested in understanding how the process of...

Homework Statement The issue I have is that I am asked to estimate the activity of a small source of gamma radiation; the question is written below: 'A small source of gamma radiation is placed at a distance of 160mm from a detector of area 18mm^2. The count recorded on the detector after 30...

According to my textbook, the decay constant is the probability that a radionuclide will decay in any second (hence the unit s^-1) and so the total number of radionuclides decaying at any second, i.e. the activity, is λN but this is also the rate of change of N thus dN/dt = -λN Surely...

Homework Statement The age of the dead sea scrolls was measured using radiocarbon dating. If the measurement gives a ratio of 0.78 for the ratio of the activity in the sample to the activity in a sample of corresponding live material of similar mass, calculate the age of the scrolls...

Homework Statement This problem involves calculating the age of plant material from which 3 radioactive disintergrations per minute per gram of carbon are detected. During its lifetime, the plant took in carbon from the atmosphere. Of this carbon, for every 1012 atoms of normal 14C, there was...

Homework Statement I have conducted an experiment and found the gradient λ of a graph to be (2.15x10^-4) +- (0.15x10^-4) The graph being ln(A) i.e. the number of disintegrations/unit time - dN/dt against time t The half-life is T(1/2) = ln(2)/λ = -3223.9 How do I find the...

Homework Statement Homework Equations N=N0e-λt The Attempt at a Solution I can do all of part (a) but I'm stuck on part (b). I don't even know where to begin. I just have no idea what to make of this question. Could someone prod me in the right direction ?

How can I efficiently calculate the amount of material decayed after a specific time in a two-step decay chain? In my specific example, I have 56Ni -> 56Co -> 56Fe. The half life of the first process is 6.1 days, the second - 77.7 days. How can I accurately calculate the amount of 56Fe that...

I am not quite sure why there are only four types of decays, alpha, beta plus and minus, and electron capture. I know that heavy nuclides undergo alpha decay because it is a fast way to loose 2 protons and 2 neutrons, also that the alpha particle is very stable. For beta plus and minus...

I can't figure this out , I've tried and tried but I was absent the day they explained this and I have no idea at all what decays/min is or any of that. I've solved 9 problems and I'm missing 4, and one of them is similar to this one that I will try to answer once you try explain this one to me...

I don't understand where radioactive decay comes from. Everything I've read discusses how the environment can influence the decay (for example, neutrons in different nuclei decay with different speeds), but I couldn't find an explanation of what is the underlying cause of the decay. If the...

Homework Statement Given the followin[Sg decay chain- X→Y→Z Solve for Nx(t), Ny(t), Nz(t) for the case of Rx(t)=\alphat and assuming Ny(t)=Nz(t)=0 Homework Equations dNx(t)/dt = -\lambdaxNx(t) + Rx(t) dNy(t)/dt = -\lambdayNy(t) +\lambdaxNx(t) dNz(t)/dt = -\lambdazNz(t) +\lambdayNy(t) The...

(original question) Does the electric charge of an isolated block of radioactive material increase, assume that all emissions are reabsorbed? Subsequent edit: I guess if the body were isolated and emissions escaped the body, a charge would build up until the capacitance of the body is...

Hi all, Was reading articles on neutron stars and black holes when I started thinking about magnetic fields. I think it is a fact that magnetic shields on Earth block out the harmful radioactive solar flares that come from the sun. So in the article i was reading it mentioned something about...

dHomework Statement the half life of U234 is 245.5 years. It decays by α emmission to Th230 whos half life is 75.38. there are 10^6 atoms of U234 and 0 atoms of Th230 at t=0. At what time will the number of atoms of each type be equal? the half life of U234 is 245.5 years and half life of...

Hi, Explain in terms of the number of nucleons and the forces between them, why argon-36 is stable and argon-39 is radioactive. My first doubt regards the number of nucleons. If a nucleon is the collective number of neutrons and protons, if we take carbon 12 for example, does it have 6 or...

As I understand it, it's not yet possible to predict/calculate, from first principles, the half-lives of radiactive decays corresponding to any particular type of atomic isotope. Can anyone confirm this? I would also be interested to know the difficulties involved in achieving this goal...

Hi, just learning about alpha and beta particles in class this week. What does it mean that the nucleus is unstable in a radioactive isotope? Is this a condition that must be present for nuclear radiation?

There are 2 radioactive balls, which have the same radius and the same weight. They are covered with absorbing layer. They are made of diffrent materials, with other half-life. What is the easiest way to recognise which is which? I had searched for the answer for a longer time and could not...

Homework Statement I learned that radio-decay is exponential; say if A decays to B with constant y1 and B decays to C with constant y2 and C is stable, N1 is nuclei in A while N2 is nuclei in B. N1 = N0e-y1(t) Homework Equations Then, I tried writing the decay equation for B, and hit...

The fact that radioactive decay and continuous compound interest end up with the same formula (with the "rate" being negative in the former and positive in the latter) seems to me to be more a result of the ubiquity of the exponential function in solving differential equations than any common...

I want to know how much radioactivity in Becquerels is produced by a typical light water reactor in one year of operation. I don't know how one would go about estimating this number. I found one reference that said 27 tons of spent fuel are generated by a typical reactor per year. But I...