Electronics

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===Particle physics===

* Electric charge is quantized: there exists a smallest positive amount of charge.

** We'll denote this with q.

** This has been more or less demonstrated experimentally, [https://arxiv.org/pdf/hep-ph/9209259 but not compellingly theoretically].

* We'll denote this smallest positive charge with q.

** All other charges are integer multiples of this quantum of charge.

** This implies a largest negative amount of charge, -q, the additive inverse of q.

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** [https://en.wikipedia.org/wiki/Bremsstrahlung Bremsstrahlung], [https://en.wikipedia.org/wiki/Synchrotron_radiation synchrotron radiation] (magnetobremsstrahlung), [https://en.wikipedia.org/wiki/Cyclotron_radiation cyclotron radiation], these are all subsets of photon emission due to charged particle accleration

* Photons are massless, and thus tend to move very quickly.

** Nothing moves faster than c, the speed of a ~~photon~~ in a vacuum.

** Nothing moves faster than c, the speed of a massless particle in a vacuum.

** c = 299792458 m/s, or about one foot in a nanosecond.

** Sometimes photons are not the fastest thing in a given medium, hence [https://en.wikipedia.org/wiki/Cherenkov_radiation Cherenkov radiation] at constant velocity (no acceleration)

* The unit of charge is the [https://en.wikipedia.org/wiki/Coulomb coulomb] (C).

** It is not an integer multiple of the elementary charge.

** The elementary charge is defined as exactly 1.602176634×10−19 C (160.2176634 zC).

===Atomic physics===

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** the effect of charge can be superimposed, and

** charged particles will flow between isolated regions of opposite charge.

===Classic Emag===

* Usable whenever distances are large enough and/or field strengths low enough that quantum effects can be ignored.

* For a manifestly Lorentz-covariant theory, one must use [https://en.wikipedia.org/wiki/Four-current four currents] and the [https://en.wikipedia.org/wiki/Electromagnetic_tensor electromagnetic tensor] or [https://en.wikipedia.org/wiki/Electromagnetic_four-potential four-potential].

** This formulation makes plain the mixing of E and B.

* An electric vector field E and a magnetic vector field B exist at all points.

* A particle having charge c (an integer multiple of e) is acted upon by the Lorentz force:

** F = c(E + v ⨯ B).

** v ⨯ B is orthogonal to the particle's velocity vector and B at the particle's position.

* The "force" on a particle is due to changes in the field.

* μ0: permeability of the vacuum = 1 / ε0c2 = 1.25663706127(20)×10-6 N/A2.

* ε0: permittivity of the vacuum = 1 / μ0c2 = 8.8541878188(14)×10-12 F/m.

====Maxwell's equations====

* ∇ ⋅ E = ρ / ε0.

* ∇ ⋅ B = 0.

* ∇ ⨯ E = -∂B / ∂t.

* ∇ ⨯ B = μ0(J + ε0∂E / ∂t).

==Current==

* When charge carriers move, we call this a current.

* The unit of current is the ampere (A).

** An ampere is equal to one coulomb per second.

*** This is roughly (but not exactly) 6.241509074×1018 e per second.

*** This is exactly 1019 e per 1.602176634 seconds.

* I = dq/dt = nAEvd

==First order: lumped elements==

An [https://en.wikipedia.org/wiki/Electronic_component component] is any discrete unit in a circuit that is doing more than linking multiple components. Elements which link components are [https://en.wikipedia.org/wiki/Wire wires], and are usually reasonably conductive (otherwise they wouldn't be very good links).

A [https://en.wikipedia.org/wiki/Electronic_component component] is any discrete unit in a circuit that is doing more than linking multiple components. Elements which link components are [https://en.wikipedia.org/wiki/Wire wires], and are usually reasonably conductive (otherwise they wouldn't be very good links).

The "lumped element model" concentrates components to single points, and assumes ideal (simple) behavior. This induces a graph of finitely many planes, and allows us to work with ODEs rather than PDEs. It's more useful IMHO to relax the concentration, and treat components as ordered cycles corresponding to their geometry. In this model, when wires intersect, they become a single wire. A wire is a node, and each pin is a node.

* Kirchhoff's Laws: corollaries of Maxwell's Laws in the low-frequency limit (wavelengths ≫ circuit size)

** First Law / Junction Rule: the algebraic sum of currents at a node is zero (what flows in must flow out)

** Second Law / Loop Rule: the directed sum of voltages around a closed loop is zero

==PCB design==

* Longer traces add inductance

* Thinner traces add more resistance than wider ones.

** For lowspeed, simple traces of length L, area A, and material resistance ρ: R = ρ(L/A)

* Wider traces add more impedance than thinner ones.

Electronics: Difference between revisions

Dank (talk | contribs)

@@ Line 4: / Line 4: @@
 ===Particle physics===
 * Electric charge is quantized: there exists a smallest positive amount of charge.
-** We'll denote this with <i>q</i>.
+** This has been more or less demonstrated experimentally, [https://arxiv.org/pdf/hep-ph/9209259 but not compellingly theoretically].
+* We'll denote this smallest positive charge with <i>q</i>.
 ** All other charges are integer multiples of this quantum of charge.
 ** This implies a largest negative amount of charge, -<i>q</i>, the additive inverse of <i>q</i>.
@@ Line 25: / Line 26: @@
 ** [https://en.wikipedia.org/wiki/Bremsstrahlung Bremsstrahlung], [https://en.wikipedia.org/wiki/Synchrotron_radiation synchrotron radiation] (magnetobremsstrahlung), [https://en.wikipedia.org/wiki/Cyclotron_radiation cyclotron radiation], these are all subsets of photon emission due to charged particle accleration
 * Photons are massless, and thus tend to move very quickly.
-** Nothing moves faster than <i>c</i>, the speed of a photon in a vacuum.
+** Nothing moves faster than <i>c</i>, the speed of a massless particle in a vacuum.
+** <i>c</i> = 299792458 m/s, or about one foot in a nanosecond.
 ** Sometimes photons are not the fastest thing in a given medium, hence [https://en.wikipedia.org/wiki/Cherenkov_radiation Cherenkov radiation] at constant velocity (no acceleration)
+* The unit of charge is the [https://en.wikipedia.org/wiki/Coulomb coulomb] (C).
+** It is <i>not</i> an integer multiple of the elementary charge.
+** The elementary charge is defined as exactly 1.602176634×10<sup>−19</sup> C (160.2176634 zC).
 ===Atomic physics===
@@ Line 41: / Line 46: @@
 ** the effect of charge can be superimposed, and
 ** charged particles will flow between isolated regions of opposite charge.
+===Classic Emag===
+* Usable whenever distances are large enough and/or field strengths low enough that quantum effects can be ignored.
+* For a manifestly Lorentz-covariant theory, one must use [https://en.wikipedia.org/wiki/Four-current four currents] and the [https://en.wikipedia.org/wiki/Electromagnetic_tensor electromagnetic tensor] or [https://en.wikipedia.org/wiki/Electromagnetic_four-potential four-potential].
+** This formulation makes plain the mixing of <b>E</b> and <b>B</b>.
+* An electric vector field <b>E</b> and a magnetic vector field <b>B</b> exist at all points.
+* A particle having charge c (an integer multiple of <i>e</i>) is acted upon by the Lorentz force:
+** <b>F</b> = c(<b>E</b> + <b>v</b> ⨯ <b>B</b>).
+** <b>v</b> ⨯ <b>B</b> is orthogonal to the particle's velocity vector and <b>B</b> at the particle's position.
+* The "force" on a particle is due to changes in the field.
+* μ<sub>0</sub>: permeability of the vacuum = 1 / ε<sub>0</sub><i>c</i><sup>2</sup> = 1.25663706127(20)×10<sup>-6</sup> N/A<sup>2</sup>.
+* ε<sub>0</sub>: permittivity of the vacuum = 1 / μ<sub>0</sub><i>c</i><sup>2</sup> = 8.8541878188(14)×10<sup>-12</sup> F/m.
+====Maxwell's equations====
+* ∇ ⋅ <b>E</b> = ρ / ε<sub>0</sub>.
+* ∇ ⋅ <b>B</b> = 0.
+* ∇ ⨯ <b>E</b> = -∂<b>B</b> / ∂t.
+* ∇ ⨯ <b>B</b> = μ<sub>0</sub>(<b>J</b> + ε<sub>0</sub>∂<b>E</b> / ∂t).
+==Current==
+* When charge carriers move, we call this a current.
+* The unit of current is the ampere (A).
+** An ampere is equal to one coulomb per second.
+*** This is roughly (but not exactly) 6.241509074×10<sup>18</sup> <i>e</i> per second.
+*** This is exactly 10<sup>19</sup> <i>e</i> per 1.602176634 seconds.
+* I = dq/dt = nAEv<sub>d</sub>
 ==First order: lumped elements==
-An [https://en.wikipedia.org/wiki/Electronic_component component] is any discrete unit in a circuit that is doing more than linking multiple components. Elements which link components are [https://en.wikipedia.org/wiki/Wire wires], and are usually reasonably conductive (otherwise they wouldn't be very good links).
+A [https://en.wikipedia.org/wiki/Electronic_component component] is any discrete unit in a circuit that is doing more than linking multiple components. Elements which link components are [https://en.wikipedia.org/wiki/Wire wires], and are usually reasonably conductive (otherwise they wouldn't be very good links).
 The "lumped element model" concentrates components to single points, and assumes ideal (simple) behavior. This induces a graph of finitely many planes, and allows us to work with ODEs rather than PDEs. It's more useful IMHO to relax the concentration, and treat components as ordered cycles corresponding to their geometry. In this model, when wires intersect, they become a single wire. A wire is a node, and each pin is a node.
+* Kirchhoff's Laws: corollaries of Maxwell's Laws in the low-frequency limit (wavelengths ≫ circuit size)
+** First Law / Junction Rule: the algebraic sum of currents at a node is zero (what flows in must flow out)
+** Second Law / Loop Rule: the directed sum of voltages around a closed loop is zero
+==PCB design==
+* Longer traces add inductance
+* Thinner traces add more resistance than wider ones.
+** For lowspeed, simple traces of length L, area A, and material resistance ρ: R = ρ(L/A)
+* Wider traces add more impedance than thinner ones.