Questions tagged [protons]

A proton is a positively charged particle which is generally considered to be a composite particle comprising of three quarks interacting through the strong force (e.g. in the standard model.)

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108
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7answers
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What's inside a proton?

What constitutes protons? When I see pictures, I can't understand. Protons are made of quarks, but some say that they are made of 99% empty space. Also, in this illustration from Wikipedia, what's ...
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Why are protons heavier than electrons?

Our teacher told us that protons are nearly 1800 times heavier than electrons. Is there any known reason as to why this is so? Or is this just an empirical value, one we do not know the reason to?
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What enables protons to give new properties to an atom every time one is added?

How does adding one more particle to the nucleus of an atom give that atom new properties? I can see how it changes it's mass, that's obvious... But how does it give that new atom different properties ...
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Why do electron and proton have the same but opposite electric charge?

What is the explanation between equality of proton and electron charges (up to a sign)? This is connected to the gauge invariance and renormalization of charge is connected to the renormalization of ...
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How do we know neutrons have no charge?

We observe that protons are positively charged, and that neutrons are strongly attracted to them, much as we would expect of oppositely charged particles. We then describe that attraction as non-...
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Theoretically, could there be different types of protons and electrons?

Me and my friend were arguing. I think there could theoretically be different types of protons, but he says not. He says that if you have a different type of proton, it isn't a proton, it's something ...
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What is the experimental evidence that the nucleons are made up of three quarks?

What is the experimental evidence that the nucleons are made up of three quarks? What is the point of saying that nucleons are made of quarks when there are also gluons inside it?
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Is a proton collision (collisions like in the LHC) visible to the human eye?

I was curious if a proton collision is visible to the human eye. (This might sound like a really basic question and forgive me if it is. I am very inexperienced in Physics and just wanted an answer ...
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Why no proton microscopes? Proton diffraction; or proton scattering experiments? Proton crystallography?

I am asking a (relatively) 'low-energy' question here, not about things like the Large Hadron Collider... There are tons of articles everywhere, including such places as Wikipedia and ScienceDirect, ...
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Are protons bigger than electrons?

In every text/ physics book that I've read, Protons are mentioned as particles that are bigger, way bigger 2000 times to be precise, than electrons...I believed that until a few minutes ago when I ...
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Proton: 2 up, 1 down quark, Neutron: 2 down, 1 up, how can Neutron: proton + electron?

I imagine that there is a pretty simple answer to my question, but I have just never gotten it straight. If a proton is comprised of two up quarks and a down, and neutrons are comprised of two down ...
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Can there be an atomic nucleus where there are more protons than neutrons?

As far as I know, number of protons is less that or equal to the number of neutrons in any atomic nucleus. But is there any possibility that there exists a nucleus where the number of protons exceeds ...
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Why the charge of the proton does not transfer to the neutron in the nuclei?

For example, when we put two objects of +10C and +20C together and then take them apart, each of them acquires a charge of +15C. In a nucleus, the protons and neutrons are stuck together. Why is it ...
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Can an electron and a proton be artificially or naturally merged to form a neutron?

My sense is that even though neutrons decay into a proton and an electron they are made up of quarks, it is not just some "merged" particle where, for example, the electron is orbiting the ...
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How is the speed of nucleons in the nucleus measured?

This article claims that "nucleons in a dense nucleus exceed 25 percent of the speed of light". How do you measure or infer the speed of nucleons in the nucleus? Note added later: I'm looking here ...
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What happens to the electron companions of cosmic ray protons?

If primary cosmic rays are made mostly of protons, where are the electrons lost, and does this mean that the Earth is positively charged? Does the sun eject protons and electrons in equal number?
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What is charge? [duplicate]

I know this isn't the right place for asking this question, but in other places the answers are so awfull.. I'm studying eletricity, so, I start seeing things like "charges", "electrons has negative ...
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How did we know that the Dirac equation describes the electron but not the proton?

I'm suddenly getting confused on what should be a very simple point. Recall that the $g$-factor of a particle is defined as $$\mu = \frac{ge}{2m} L$$ where $L$ is the spin angular momentum. For any ...
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2answers
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Why does this quiz question say that protons and electrons do not combine to form neutrons?

I read this somewhere: Where are the protons and electrons in a neutron star? When the neutron star forms, most of the protons and electrons combine together to form neutrons. But on a true/false ...
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Why does amount of protons define how matter is?

My question might sound convoluted but my mind is twisting right now so my apologies in advanced. Why is it that when I have one proton and one electron it is Hydrogen a clear flammable gas, and ...
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Position of protons and neutrons in a nucleus

According to the Wikipedia article on atomic nucleus, captioned on an impression of helium atom, it states that This depiction shows the particles as separate, whereas in an actual helium atom, the ...
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Measuring the size of the proton from the hydrogen atom spectrum?

I was reading that besides measuring the angle of ricocheted electrons bouncing off the proton to pin down its size, it is also possible to excite the electron and then measure the frequency of the ...
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Why is an electron negatively charged, and what is the difference between negative and positive charges?

Nobody has yet defined the actual meaning of a charge, or why a negative charge is different from a positive charge. Everybody knows that positive charge is due to protons and negative charge is due ...
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What's with the very slightly larger mass of the neutron compared to the proton?

Neutron mass: 1.008664 u Proton mass: 1.007276 u Why the discrepancy? On a related note, how does one go about measuring the mass of a neutron or proton, anyway?
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What do we know about the interactions between the protons and neutrons in a nucleus?

In a nucleus, the strong nuclear force causes interactions between protons and protons, between neutrons and neutrons, and between protons and neutrons. What do we know about this interaction? ...
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Is the nucleus smaller than the electron?

In the classical incorrect 'billiard ball' model of the atom, electrons are often drawn as smaller balls than the protons and neutrons in the nucleus. However from quantum mechanics we know the ...
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Quarks in a hadron: where does the mass come from?

We know that the sum of the masses of the quarks in a proton is approximately $9.4^{+1.9}_{-1.3}~\text{MeV}/c^2$, whereas the mass of a proton is $\approx931~\text{MeV}/c^2$. This extra mass is ...
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Why is the mass of the proton such a precise value?

Why is the mass of the proton such a precise value? A proton is composed of 3 net valence quarks and what is often described as "binding energy" or "a zillion gluons and quarks and anti-...
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What is the reason for the shift in balance between neutrons and protons in the early universe?

In the book of The First Three Minutes by Weinberg, on pages 106-107, it is stated that SECOND FRAME. The temperature of the universe is 30,000 million degrees Kelvin [...] The nuclear particle ...
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In which experiment did protons seem to consist of infinite amount of quarks?

In this video Richard Feynman is telling that in some experiment it seems that the proton should consist of infinite amount of quarks. What is this case he's mentioning? Is it solved now?
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Is an alpha particle four nucleons or dodecaquark?

In a $\alpha$ particle, do the 4 nucleons stay distinct in any meaningful manner, or is it more accurately considered to be a hadron composed of 12 valence quarks that are not subdivided into nucleons?...
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Why does the nucleus not repel itself? [duplicate]

If the nucleus is densely positively charged, why don’t the protons in the nucleus repel from each other and move towards the orbiting electrons? Because each proton is not only being repelled by the ...
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1answer
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How accurately is it known that protons have the same charge as electrons?

Recently, I claimed that the proton and electron have the same charge, and that this has been experimentally verified up to $1$ part in $10^{26}$. This belief was naively based on CODATA's 2014 ...
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Why is a proton assumed to be always at the center while applying the Schrödinger equation?

Why is a proton assumed to be always at the center while applying the Schrödinger equation? Isn't it a quantum particle?
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Does the Electric Field Instantaneously vanish during an Electron Capture?

When an Electron Capture occurs a Neutron and a Neutrino are formed. Prior to this process due to the presence of the proton and electron an electric field must've existed however as soon as this ...
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Is there a term for electron capture outside the nucleus?

My textbook says that electron capture is when an electron is 'captured' by a proton in the nucleus which causes them to turn into a neutron and an electron neutrino. The name kind of suggests it only ...
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1answer
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Who (and Why) started the “electrons are negative, protons are positive” convention? [duplicate]

For some reason everyone labels electrons using a minus sign and protons using a positive sign, even though the opposite seems more intuitive: Who started the convention that electrons should be "...
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The life of proton [closed]

I have two questions regarding protons 1) Wikipedia says Mean lifetime of a proton $>2.1×10^{29}$ years (stable) Obviously this means practically nothing happens to a proton, but what does ...
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1answer
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From which dimensionful constants does proton mass arise?

It is well known that the most of the proton (or any other hadron with light quarks) mass is not made up from quark masses, but it is dynamically generated by QCD mess inside. I've also heard that, ...
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0answers
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What is the cause of the minor mass difference between the proton and the neutron?

As known, the proton is from two up and a single down quark, while the neutron is from a single up and two down quarks. The down quark is a little bit more massive and the up, and so the neutron is ...
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Density of a proton

I was doing some exercises the other day, when I came across this question in my book: A proton weighs about 1.66 x 10-24 g and has a diameter of about 10-15 m. What is its density in g/cm3? As ...
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What is the difference between a neutron and hydrogen?

Differences? They are both an electron and a proton, since the neutron decays to a proton and an electron, what's the difference between a neutron and proton + electron? so is it just a higher binding ...
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How big of a neutron star would be needed to form a quark star inside of it?

A quark star is a hypothetical type of compact exotic star composed of quark matter. These are ultra-dense phases of degenerate matter theorized to form inside particularly massive[citation needed] ...
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Proton therapy in cancer treatment

Why are protons used in cancer therapy ? Is there any advantages compared to classics X-rays treatment or electron treatment ?
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How do I know the proton isn't made of 3 anti-down quarks?

I have a proton, how do I know that it is made of 2 up quarks and 1 down quark or if it is made of 3 anti-down quarks, each with different color charges? This question is also applicable to the ...
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2answers
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We know that the protons in a nucleus are positively charged. So why does the nucleus stay intact? [duplicate]

We know that the protons in a nucleus are positively charged, whereas the neutrons do not possess a charge; we also know that unlike charges attract. So why does the nucleus stay intact, even though ...
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1answer
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Proton Radius Puzzle, Is it possible that proton's radius differ depending on how you measure it? What does that even mean?

I just read this NewScientist article, and I was stunned by its results. So I found the original paper here on arxiv. In the introduction of the paper it is stated: The recent determination of the ...
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Addition of Angular Momementa in deeply bound situations, proton spin crisis

In Landau and Lipshitz's introductory book on Quanum Mechanics, "Quantum Mechanics Non-Relativistic Theory, Third Edition: Volume 3", chapter XIV (page 433 in the edition on Amazon) is "Addition of ...
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1answer
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If protons and electrons had similar masses

If electrons and protons had the same mass, would they still be in a stable orbit around their barycenter, or would they eventually collide? Similarly, a positronium(or protonium) only lasts extremely ...
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Why is Neutron Heavier than Proton? [closed]

This is Neutron decay: $$n^o \to p^+ + e^- + \overline {\nu_e}.$$ and this is proton one: $$p^+ \to n^o + e^+ + \nu_e$$ so when the $e^+ =e^-$ and $\nu_e=\overline {\nu_e}$ why $n \not= p$? my idea ...

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