Negatively charged particle with spin 1/2. A component of mundane terrestrial matter, and part of all neutral atoms and molecules. It has a mass about 1/1800 that of a proton. Its antiparticle is the positron.
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2answers
59 views
Collision between a photon and an electron
Looking through this AP Physics question, I was struck by how the 'collision' between a photon and electron looks so much like a macroscopic collision. Is this even physically possible?
Look at the ...
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0answers
16 views
Single electron pumps, superconducting energy gap
I am seeking to find out how many electrons per gate cycle are pumped at different temperatures. The Single Electron Pump is made out of Al, with a $T_c=1.2\,\mathrm{K}$. This single electron pump is ...
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2answers
81 views
Currents and the Speed of Light
Why is it that currents don't flow at the speed of light, but rather significant ratios of the speed of light.
I don't have any formal reasoning as to why they would flow at the speed of light-I just ...
9
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2answers
151 views
What happens in electron-electron collisions?
What are the results of high energy electron electron collisions? Are other particles created?
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0answers
44 views
Is this picture of the electron dipole moment correct?
It's the electron spinning on its axis, and a magnetic moment shoots up. The direction of the North-South is opposite what I thought it should be. Why is the vector arrow pointing from North to ...
5
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1answer
69 views
Do electrons need specific energies to excite electrons
Photons need specific energy levels, equal to the difference between two energy levels to excite an electron in an atom. Is this the same case with electrons that collide with atoms?
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1answer
42 views
Why doesn't intensity of light affect the emission of electrons?
So electrons of specific atoms have a minimum amount of energy needed to escape the atom, called the work function, W. Now let's say that you emit a certain frequency of light, and $hf<W$. However, ...
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1answer
56 views
Distinguish electron-like and hole-like orbits in reciprocal space, with reference to the Brillouin Zones
So I have a solid state and thermodynamic exam next week and I've been going through some of the previous exams from years gone by to prepare. I came across this question "Distinguish electron-like ...
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2answers
31 views
A question on lewis model
Electron affinity of chlorine = -349 kJ per mole. And, first ionization energy of sodium = 496 kJ per mole while energy required for combining= 147 kJ per mole.
Isn't it a contradiction against ...
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0answers
61 views
Neutron decay and bet on the honor of physicists [closed]
As part of a bet which arose from a discussion between a friend of mine (physicist) and me (electrical engineer) I betted against him, I could easily find a simple question that doesn't involve more ...
3
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1answer
90 views
What is the math showing that the time reversed version of an electron is a positron? (+general time reversal question)
As in Wheeler's One Electron Universe idea, how do you show that electrons and positrons are time-reversed versions of each other? Do you just apply time reversal to an electron and out pops a ...
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2answers
77 views
Definition of electric charge and proper explanation
Is there a definition of electric charge and proper explanation of it?
It is said "Electric charge is the physical property of matter that causes it to experience a force when close to other ...
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1answer
24 views
Charge gained due to photoelectric effect [closed]
Here I think, one beam will knock out just one electron. So, I am not able to even understand what the question says. Please someone give a hint as to what the question asks...
As source of the ...
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1answer
54 views
Difference between atom and elementary particle questioned
Hydrogen ion doesn't have one electron which clearly mean that it has only one proton..So hydrogen ion is only a proton. Am I right, please make it clear. If hydrogen ion and proton are same that how ...
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0answers
22 views
Ballistic Conduction - Difference between Bosonic and Fermionic Transport
Ballistic Conduction is the phenomenon of an ideal conduction environment for quantum particles - for electrons the Ballistic Conduction is not infinity, but is proportional to the difference between ...
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3answers
139 views
Why do people claim electrons are accelerating
A lot of text books mention that one of the reasons that classical mechanics failed to explain atomic and subatomic processes is that electrons which accelerate should release energy in the form of ...
3
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2answers
74 views
Transfer of electron energy to atoms (heating up of matter by absorption of photons)
If an electron absorbs a photon to get exited to a higher energy level, it should either come back to same state or any other lower state by emitting the required photon. How then can there be a net ...
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1answer
45 views
Understanding drift velocities in currents
I have a doubt about the understanding of drift velocities in a current. My problem is that the textbook speaks very loosely about this. It's like: "well, if we apply a field $E$ then the charges will ...
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1answer
42 views
Joule heating due to the (slow) electron drift velocity?
I understand the concept of why the signal speed is higher than the electron drift velocity, but I can't understand the concept of joule heating. If electrons move slow then how do they produce a lot ...
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3answers
90 views
Why doesn't a stationary electron lose energy by radiating electric field (as per coulomb's law)?
If an electron in a universe constantly generates an electric field why does it not get annihilated ? I am confused because I read that an accelerating charge radiates and loses energy. So, why won't ...
3
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2answers
153 views
Why the K shell only contains 2 electrons?
It is written in my quantum physics book that the K shell contains only 2 electrons due to the Pauli principle.
I know that if $n = 1, l = 0, m = 0$, then the Hilbert space associated to the spin is ...
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1answer
66 views
Is speed of electrons in atoms a constant during explosions? [closed]
E.g. in exploding nuclear bomb or some other big explosions.
I mean if the speed of electrons as waves/particles is a constant or changes according to other "forces" involved?
2
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0answers
34 views
Is it reasonable to interpret the Lamb shift as vacuum induced Stark shifts?
This is a pretty hand-wavy question about interpretation of the Lamb shift. I understand that one can calculate the Lamb shift diagrammatically to get an accurate result, but there exist ...
3
votes
2answers
74 views
Regarding the free electrons on the conductor
In a metal, why don’t the free electrons fall to the bottom of the metal due to gravity?
Also, charges in a conductor are supposed to reside on the surface so why don’t the free electrons all go to ...
2
votes
3answers
146 views
If photons can be absorbed by electrons, wouldn't that mean light has a charge? [duplicate]
I am a biochemistry and molecular biology major. If photons can be absorbed by electrons, wouldn't that mean light has a charge? Electrons only attract positive charges. Isn't it?
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1answer
37 views
Planes of graphite crystal on diffraction experiments
When doing electron diffraction on graphite (a popular experiment for students at universities) always diffraction at these two planes with distances $d_1$ and $d_2$ are observed:
But a plane ...
2
votes
0answers
27 views
Electron Spin Resonance and Free electrons
When performing an experiment to observe electron spin resonance, we use DPPH molecules as they contain an unpaired electron on one of the N atoms.
My question is, why cant free electrons be used in ...
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1answer
52 views
B-field and Magnetic forces, speed of a particle
Let's say I have a particle moving perpendicular to a uniform magnetic field of magnitude $x \ T$, and it moves in circle with a fixed radius. How do I find the speed of this electron? Initially I ...
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1answer
115 views
How electrons act under rotating magnetic field?
I study Power Engineering in University. Today I asked my lecturer to explain me exactly how atom's electrons act under spinning rotor's magnetic field, that generated dynamic electricity. But he even ...
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0answers
67 views
An electron has an initial velocity in B and E field [closed]
An electron has an initial velocity of (14.5j + 18.5k) km/s and a constant acceleration of (1.60×1012 m/s2)i in a region in which uniform electric and magnetic fields are present. If B =(400μT)i, find ...
4
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2answers
167 views
Do protons exchange photons with electrons?
I'm sorry for this question but, I just don't get it. According to the electromagnetic field theory, electrons repel each other by exchanging photons. How do protons attract electrons, by photon ...
3
votes
1answer
119 views
Path of an electron through an electric circuit
When a potential difference is applied across a conductor, and if an electron moves from the negative terminal of the battery and reaches the positive terminal, then I want to know if the electron ...
0
votes
3answers
114 views
Couldn't we measure electrons with good enough technology? [duplicate]
I am a bit confused about the Heisenberg's Uncertainty Principle - just read about it in How to Teach Physics to Your Dog, by Chad Orzel. He states that the reason electrons can't be measured is ...
2
votes
2answers
160 views
When drift velocity equals thermal velocity?
In some papers, I can see the drift velocity of electrons equaling thermal velocity. Can anyone tell me when both almost equal each other?
4
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1answer
332 views
Can electrons move through vacuum?
I studied that electronics is the branch of physics which deals with the practical applications of moving electrons through vacuum, semi-conductors and gasses. Can electrons move through vacuum?
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0answers
29 views
pressure required for displacing a single electron off a crystal
I need to know this for my project- "power generation using the pressure applied on a keypad of a mobile electronic device". How much pressure does it take to displace a single electron off its ...
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2answers
129 views
Why is electron presented in books, pictures as a sphere?
Why is electron presented in books, pictures as a sphere, when in fact it's not?
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0answers
27 views
Microscopic fields inside a conductor
In a neutral conductor if we assume electrons as point charges, the electric field in the space between them cannot be identically zero. This microscopic field may be very weak. What if we were very ...
2
votes
1answer
62 views
Absorption cross section for direct dissociation and predissociation - Photoelectric absorption
Why the absorption cross section in direct dissociation process is wide and structureless while the absorption cross section in the predissociation process is structured and containing lines which are ...
2
votes
0answers
44 views
Bragg reflected electrons
Could you explain how does bragg reflection happen for electrons? What does it mean that when they satisfy Laue condition? This already is asked in Physics SE. They are Bragg reflected in the opposite ...
3
votes
3answers
200 views
The Dual Nature of Matter
I can't seem to understand the dual nature of matter completely.
If electrons have a wave nature, then if two electrons were to collide, wouldn't they undergo interference and form an electron wave ...
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0answers
24 views
What is the source for magnetic energy? [duplicate]
"The electron around the nucleus is in a quantized energy level and can change it only if an external interaction intervenes." That is OK but when there is a magnet, it has energy of attracting iron ...
2
votes
2answers
65 views
Empirical bound on sum of electron and proton charge
Followup to "Why do electron and proton have the same but opposite electric charge?".
It is argued that even a tiny residual charge would result in huge amounts of electricity in bulk matter, ...
2
votes
1answer
62 views
A question about how light hits a surface
my question is about how photons travel from a light source and hit an object.
When you look at an object being hit by light the whole surface becomes brighter.
What i'm trying to understand is why ...
0
votes
2answers
550 views
Frequency of an Electron
My question is very simple.
If frequency is defined as the cylces per unit time, Then what is meant by "Frequency of an Electron" ? If the rotation of electron around a nucleus is considered then, ...
0
votes
2answers
85 views
Electron mass changes with website
When particles mass can be changed by changing the website, then how to calculate with confidence?
For example:
Google: electron mass = 9.10938 188 × 10$^-31$ kilograms
Wikipedia: electron mass
...
2
votes
2answers
202 views
Flow of electrons in a circuit
When the electrons flow in a circuit, so are those the electrons from the battery or are those the electrons of conductor like copper wire, etc..which are flowing in the circuit?
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6answers
1k views
What would happen if Large Hadron Collider would collide electrons?
After some reading about the Large Hadron Collider and it's very
impressive instruments to detect and investigate the collision results,
there is a remaining question.
What would happen if the ...
2
votes
1answer
156 views
Positive test charge
Protons have positive charge on them. Protons aren't mobile. So how can a positive test charge move from the negative terminal of a cell to the positive terminal and gain electric potential energy? ...
1
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2answers
138 views
Typical operators in tight binding
Let the tight-binding Hamiltonian be $\sum\limits_{ij} {{t_{ij}}\left| i \right\rangle \left\langle j \right|}$. Where ${\left| i \right\rangle }$ is the atomic orbit at lattice site $i$.
My question ...
