Activity Definition and 193 Threads

Hello evryone, In the MCBEND simulation I've conducted, I have found the dose rate of a gamma source in microSieverts per hour (µSv/h). I also know the distance between the detector and the source. How can I calculate the source activity or strength from this information? Thank you, Best wishes

Anyone ever talk introducing about a problem of the week. Where a user actually gets several attempts at an answer. I'm talking about a legitimate quiz type setup, complete with multiple choice automated system...not hidden responses. They did this at Brilliant and it was great engagement...

https://volcano.si.edu/volcano.cfm?vn=351020 The Street reported, "The last time the Nevado del Ruiz volcano was active, it erupted and killed 23,000 people in Colombia, wiping out the town of Armero in the process." Pay attention to volcanoes in the neighborhood and be prepared to...

In a study published in the journal Earth and Planetary Science Letters, researchers say their analysis provides evidence that the oxygen-deprived oceans precipitated two mass extinctions around 259 million and 262 million years ago during the Middle Permian Period. "We are studying the...

In the textbook Electrochemical Systems by Newman and Alyea, Chapter 14: The definition of some thermodynamic functions, chemical potential of component (ionic or neutral) is written as a function of absolute activity: $$\mu_i=RT\ln(\lambda_i)\tag1$$ where ##\lambda_i## is the absolute activity...

In the textbook Electrochemical Systems by Newman and Alyea, chapter 14: The definition of some thermodynamic functions, chemical potential of component (ionic or neutral) is written as a function of absolute activity: $$ \mu_i = RTln(\lambda_i) \tag {1} $$ where ##\lambda_i## is the absolute...

Andrew Wulfeck (FOX Weather) - Alaska officials raise alert level for volcano after increase in earthquake activity Wed, February 22, 2023 at 6:47 PM EST https://www.yahoo.com/news/alaska-officials-raise-alert-level-234711944.html https://www.avo.alaska.edu/activity/Trident.php...

TL;DR Summary: What is the activity of 0.000001 mL Rn-222? Trying to do a quick calculation of the activity of 0.000001 mL of Rn-222 and I'm not ending up with what I expected.

https://www.msn.com/en-us/weather/topstories/u-s-volcano-that-s-been-dormant-for-more-than-800-years-showing-signs-of-life/ar-AA13s3xt It's also unusual.

I am studying about components of a system. Activity-: It is What entities do to cause changes is activity. It is represented by time period of a specified length. Event-: Event is defined as an instantaneous occurrence that might change state of the system. Endogenous events occurs within...

I found something I think does not make sense. Decay constant of A: $$\lambda_{A}=\frac{ln~2}{t_{\frac 1 2}}$$ $$=\frac{ln~2}{10\times 365 \times 24 \times 3600}$$ $$=2.2\times 10^{-9} / s$$ Initial activity of A = ##\lambda_{A} N_{\text{initial}}## = 2.2 x 10-9 x 1.29 x 109 = 2.84 Bq Then...

I know that as the concentration of substrate increases, the enzyme activity increases because there are more substrate molecules to react on (but at an increasingly slower rate). Would the same reasoning work with volume? Thanks!

Suppose one knows well the laws of physics but knows nothing about computers and IT. Would one be able to deduce how a computer works only by studying its hardware? Could one rebuild the software code and understand its meaning only by looking at the internal flow of bits in its CPU?

When we want to determine the radioactivity of a nucleus, we usually determine the counts detected using say a Geiger counter. The count rate is then usually used as the disintegration rate i.e. the activity of the nucleus. However, say now we wish to measure the activity of Radon 222 using...

Clearly, they used the binomial expansion on this; however, I cannot figure out why [G] is sandwiched by the epsilon inverses: $$\varepsilon^{'-1}=1/(\varepsilon+i\epsilon_{0}[G])\approx(1-i\epsilon_{0}[G]\varepsilon^{-1})\varepsilon^{-1}$$

Hi everyone! I have to calculate the activity of ##Cl^{-}## I have a solution formed by ## Na_{2}SO_{4}## 0.0016 m + ##NaCl## 0.0014m + ##FeCl_{3}## 0.0012m I calculated the ionic strength ##I## ##I=0.0134## The activity of the chloride ion is ##a_{Cl^{-}}=m_{Cl}*\gamma _{Cl}## But I don't...

When I use the concept of activity to express the equilibrium constant expression, for either equilibrium pressures or concentrations, the units cancel and the value of K has no units (which is how K is customarily reported). But because of the difference in reference states (the reference...

Hi, I've been reading about radiation detectors (manly form Knoll's book), but there is something I don't understand. Radiation detectors are of very different nature, but they all share a common process to detect a type of radiation: - I have a control volume - The incoming radiation interacts...

I've written out the half reaction 8e- + 9H+ + SO42- = HS- + 4H2O and I know the logK = 4.25 (that's the constant mentioned in the prompt) I've written out the equilibrium statement of 10^4.25 = ([x^1/8]*[H2O^1/2])/([10x^1/8]*[e-]*[(10^-8.2)^9/8] However, from there, it seems like I have two...

Hi there So I have had a go at this question but I'm not confident that I have done the last 2 parts of this question right? Can anyone please see if this is what you do to get the values? Any help would be appreciated! Thanks

How do I determine which group is dash (into the page) and which is wedge (out of page)? Won't that literally change which isomer it is? How to determine optical activity then? (I believe that in order for something to be optically active it has to be an enantiomer--a non-superimposable mirror...

Anise extracts contain Lignin-Carbohydrate complexes (LCs), which have been found to have anti-viral effects according to this article (DOI: 10.1271/bbb.100645 ). However, from what I understood by going quickly through the article, the scientists applied the extract directly onto the cell...

From what I've understood, we know sun's activity well enough that we can make some good predictions about it for a decade or so to the future. But is it theoretically possible that all the measurements that we have been able to make about the solar cycles and their effect on our climate, are in...

My explanation is : for ph=pka , the number of two ionic forms[A-] and [HA] are equal, then, for ph>pka,[A-]>[HA], the gratient gets smaller when ph is increased, and also, for ph<pka, [A-]<[HA], the slope is becoming larger when pH is increasing . Would u like to have a look of my explanation...

Problem Statement: Question: Calculate the activity in Bq of 1g of (238-94 Pu).Would love some help with the working. The final answer is 6.35 x 1011 Bq Relevant Equations: Atomic Mass of Pu = 238.049550u Previously calculated: λ=2.51x10-10 s-1 Pls help

I’m confused because there are two equations: 1) A=λN 2) A=A0exp^-(λt)If half-life increases, λ decreases, and A decreases according to 1); but, If half life increases, λ decreases, hence exp^-(λt) decreases, A should decreases according to 2)Why is this so? Where went wrong? Thanks!

Consider chain of two radioactive decays ##A \to B\to C##. The equation that regulates ##N_B## is $${\frac {\mathrm {d} N_{B}}{\mathrm {d} t}}=-\lambda _{B}N_{B}+\lambda _{A}N_{A}$$ I can't understand why the activity of ##B## is get as ##\lambda_B N_B##, for example at page 20 here...

Greeting, I am trying to figure out how can I include the activity of a Co-60 source in MCNP code. I have the following problem Co-60 source in a cylinder surrounded by concrete. I just need to know how to include the source activity and whether it should be in Bq or Ci. Thank you in advance

Hi, I've been looking at the optics of ##\alpha##-quartz which comes in two parities, left and right. Quartz is optically active which means that the plane of a linearly polarized beam propagating along the optic axis is rotated by an angle proportional to the distance traveled. I would like...

Hello - I am wondering abut the meaning of chemical activity. Most definitions are something along the lines of "effective concentration," which is fine until you have a real concentration in a lab, and you don't know if you need to calculate the concentration or "effective" concentration of the...

Two graphs are given But i don't know how to explain each of them?? first one is curved because there is not enough substrate maybe ??

Homework Statement Consider the following reaction $$\mathrm{Ni^{2+}_{(aq)} + H_2S_{(g)} \to Ni_{(s)} + S_{(s)} + 2H^{+}_{(aq)}}$$ What are the activities of the terms in the reaction? Homework Equations The activity is defined as ##a = c/c^\circ## in ##\mathrm{ mol \, dm^3}## 3. The...

Hi , this is my equation : μA= μA0 + RTlnaA A is the asphaltene in toluene solution . i want to calculate μA in different temperatures. where can i get μA0 and aA? tables? other equations? μA0 is the standard chemical potential of asphaltene and aA is the asphaltene activity in solution.

I am picking this up as a continuation and extension of the idea laid out e.g. in @davenn 's thread "The Sun today - 9 July 2017 - nice spot group" https://www.physicsforums.com/threads/the-sun-today-9-july-2017-nice-spot-group.919696/ See also (for continuity purposes)...

The definition of activity is: $$\mu _{i}=\mu _{i}^{0}+RT\cdot \ln a_{i}$$ where μi is the chemical potential of i in current state and μi0 is the chemical potential of i in standard state. The current and standard state have the same temperature or can their temperature differ? If their...

I have to make a project for school, so I thought that i can make a static electricity car. I wanted to make a car, and stick/put a material behind the car which creates a charge, and then take another material which creates a charge, and rub it. As it creates static electricity, the cars...

What's the difference between activity of a radioactive sample and the decay constant. Both are measured in second inverse. Please distinguish among the two?

Hello there, I have a question that I just can't seem to solve by myself (although compared to the other threads here it seems quite simple) I did some FDG-PET scans for my master thesis: I inject a certain dose of F18-FDG and prepare these injections by measuring the right dose using a...

Activity (in Bq) of 1 mol of a radionuclide is given by formula: A = NA x ln(2) / t1/2 = 0.693 x NA / t1/2 where NA is Avogadro number and t1/2 the half-life (in seconds) Why don't we use simply A = 0.5 x NA / t1/2 ? After all, t1/2 means that, after that time, half of atoms will have decayed...

I'm updating some poorly written lab activities for an online physics class that I have been given, and I am going through the experiments and doing them myself to better write them. I came across this one, and I have no idea what the results are supposed to be. It comes after the chapter on...

Homework Statement Imagine that you are conducting an activity with laser to create an interference pattern. Use the appropriate equations to predict two ways to change the interference pattern in order to have closer fringes. Explain your predictions. Change in X = L(Lambda) / d Homework...

Homework Statement Carbon-14 decays by β emission and has a half-life of 5570 years. What is the decay constant of carbon-14? What is the activity of 1 g of carbon if 1 in 1012 atoms are carbon-14? After what time will the activity per gram have fallen to 3 Bq? Homework Equations λt½ = ln(2)...

Some activity you do while working to refresh your brain. It is actually a serious thing. I encourage anyone not familiar to learn about. I have desktop versions of field sports I play eg miniature basketball hoop, Velcro dart board, desktop catapults, and some mindless funny YouTube sub's eg...

Hello, one of my friends came over to get some help on a homework problem, and it went past over my head I am pretty good with stats, just don't know how to approach this to help him out. So a radionuclides' activity (Cesium 137) is measured in the year of 1981, (no date just year), and its...

good evening everybody! i'm studying these days the nuclear activity and this amazing world where an atom try to find its/her stability ! so i came across the famous radiations but then stopped by something i didn't quite understand! when an atom release a beta radiation a negative one for...

Hi! I just keep having a hard time looking for the formula stating the relationship between half life, the initial number of unstable nuclei and the initial activity, can someone help me on that ? To be more specific, here is a problem which can be solved using that formula: "A substance has a...

Homework Statement A patient is treated for cancer using radiation from a cobalt-60 unit. Exactly 1.5 years later another patient is treated for the same cancer using the same co-60unit previously used. How much longer would treatment be for the second patient? Homework Equations Decay...

https://www.researchgate.net/publication/301759171_Evidences_for_higher_nocturnal_seismic_activity_at_the_Mt_Vesuvius abstract We analyze hourly seismic data measured at the Osservatorio Vesuviano Ovest (OVO, 1972–2014) and at the Bunker Est (BKE, 1999–2014) stations on the Mt. Vesuvius. The...

http://www.ibtimes.co.uk/volcanologists-fear-infamous-tenerife-volcano-will-erupt-after-100-earthquakes-are-recorded-1584962 Keep an eye on that one.