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.
7
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1answer
172 views
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 ...
0
votes
0answers
36 views
Why aren't there more than three generations of the leptons and quarks? [duplicate]
There are three generations of electrons, neutrinos, and quarks. The second and third generations of electrons and quarks are unstable and decay into lighter particles.
Why are there exactly three ...
1
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0answers
9 views
Why are there two quasi Fermi levels and only one Equilibrium Fermi level?
I am reading a book and I'm trying to understand the concept of quasi Fermi levels.
For example,
A steady state of Electron Hole pairs are created at the rate of $2*10^{13} cm^{-3}$ per $\mu S$ in ...
1
vote
1answer
26 views
Dirac electron polarity?
according to
Spin of an electron
Dirac said the electron has Two possible spins if i'm correct.
Do Electrons have polarity? measurable by its Dirac spin or probabilistically by its quantum states?
-1
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0answers
12 views
secondary electron gain and secondary electron yield [duplicate]
The context of the question is an electron microscope. Can someone explain me the difference between secondary electron gain and secondary electron yield?
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0answers
20 views
Secondary electron gain vs. secondary electron yield
The context of the question is an electron microscope.
Can someone explain me the difference between secondary electron gain and secondary electron yield?
1
vote
1answer
44 views
How is the energy of an electron-shell related to the speed of electrons in that shell?
I am trying to gain an intuitive picture of what is referred to by "electron-shell energy". I have read that outer electron shells have higher energy than inner electron shells, and this seemed to ...
0
votes
0answers
20 views
Interaction of SEM electron beam with material
When an electron incident on a material what is the interaction
between electron and material?
The question is about SEM (Scanning electron microscope).
So, the electrons beam will interact ...
0
votes
2answers
56 views
Do excited electrons drop back to same quantum state?
I'm trying to wrap my head around spectroscopy, therefore, I am looking for as complete an answer as possible here, hence why I have broken the question into a different points.
Here is what I know ...
1
vote
2answers
74 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 ...
1
vote
0answers
21 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 ...
1
vote
2answers
86 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 ...
11
votes
2answers
199 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
48 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
votes
1answer
75 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?
0
votes
1answer
43 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, ...
1
vote
1answer
70 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 ...
0
votes
2answers
39 views
A question on lewis model [closed]
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 ...
3
votes
1answer
98 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 ...
0
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2answers
153 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 ...
-1
votes
1answer
28 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 ...
0
votes
1answer
63 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 ...
1
vote
0answers
24 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 ...
2
votes
3answers
153 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
votes
2answers
91 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 ...
1
vote
1answer
51 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 ...
1
vote
1answer
54 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 ...
0
votes
3answers
117 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
votes
2answers
162 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 ...
-2
votes
1answer
76 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
votes
0answers
35 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
88 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
222 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?
3
votes
1answer
46 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
29 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 ...
1
vote
1answer
73 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 ...
0
votes
1answer
166 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 ...
0
votes
0answers
70 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
votes
2answers
190 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
127 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 ...
1
vote
3answers
130 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
217 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
votes
1answer
339 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?
1
vote
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 ...
0
votes
2answers
134 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?
1
vote
0answers
29 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
67 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
46 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
222 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 ...
1
vote
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 ...
