Data file format by Ciro Santilli 35 Updated +Created
Finite field by Ciro Santilli 35 Updated +Created
A convenient notation for the elements of of prime order is to use integers, e.g. for we could write:
which makes it clear what is the additive inverse of each element, although sometimes a notation starting from 0 is also used:
For fields of prime order, regular modular arithmetic works as the field operation.
For non-prime order, we see that modular arithmetic does not work because the divisors have no inverse. E.g. at order 6, 2 and 3 have no inverse, e.g. for 2:
we see that things wrap around perfecly, and 1 is never reached.
For non-prime prime power orders however, we can find a way, see finite field of non-prime order.
Video 1.
Finite fields made easy by Randell Heyman (2015)
Source. Good introduction with examples
Pound sterling by Ciro Santilli 35 Updated +Created
Cross section (physics) by Ciro Santilli 35 Updated +Created
The neutron temperature example is crucial: you just can't give the cross section of a target alone, the energy of the incoming beam also matters.
Peano existence theorem by Ciro Santilli 35 Updated +Created
Extended Euclidean algorithm by Ciro Santilli 35 Updated +Created
Intelligence agency by Ciro Santilli 35 Updated +Created
English idiom by Ciro Santilli 35 Updated +Created
Oscilloscope by Ciro Santilli 35 Updated +Created
Video 1.
FNIRSI 1014D review by Kerry Wong (2022)
Source. One of the cheapest oscilloscopes available at the time.
Maxwell's equations by Ciro Santilli 35 Updated +Created
Unified all previous electro-magnetism theories into one equation.
Explains the propagation of light as a wave, and matches the previously known relationship between the speed of light and electromagnetic constants.
The equations are a limit case of the more complete quantum electrodynamics, and unlike that more general theory account for the quantization of photon.
The equations are a system of partial differential equation.
The system consists of 6 unknown functions that map 4 variables: time t and the x, y and z positions in space, to a real number:
  • , , : directions of the electric field
  • , , : directions of the magnetic field
and two known input functions:
  • : density of charges in space
  • : current vector in space. This represents the strength of moving charges in space.
Due to the conservation of charge however, those input functions have the following restriction:
Equation 1.
Charge conservation
.
Also consider the following cases:
  • if a spherical charge is moving, then this of course means that is changing with time, and at the same time that a current exists
  • in an ideal infinite cylindrical wire however, we can have constant in the wire, but there can still be a current because those charges are moving
    Such infinite cylindrical wire is of course an ideal case, but one which is a good approximation to the huge number of electrons that travel in a actual wire.
The goal of finding and is that those fields allow us to determine the force that gets applied to a charge via the Equation "Lorentz force", and then to find the force we just need to integrate over the entire body.
Finally, now that we have defined all terms involved in the Maxwell equations, let's see the equations:
Equation 2.
Gauss' law
.
Equation 3.
Gauss's law for magnetism
.
Equation 4.
Faraday's law
.
Equation 5.
Ampere's circuital law
.
You should also review the intuitive interpretation of divergence and curl.
Pin header by Ciro Santilli 35 Updated +Created
These often come pre-soldered on devboards, e.g. and allow for easy access to GPIO pins. E.g. they're present on the Raspberry Pi 2.
Why would someone ever sell a devboard without them pre-soldered!
Figure 1.
6x1 pin header
. Source.
Figure 2.
Underside of a Raspberry Pi 2
. Source. At the top of this image we can clearly see how the usually pre-soldered pin header connectors go through the PCB and are soldered on both sides.
Weston cell by Ciro Santilli 35 Updated +Created
Covariance and contravariance of vectors by Ciro Santilli 35 Updated +Created
Eigenvector by Ciro Santilli 35 Updated +Created
Directed graph by Ciro Santilli 35 Updated +Created
Digital Light Processing by Ciro Santilli 35 Updated +Created
Direct democracy by Ciro Santilli 35 Updated +Created
Cult leader by Ciro Santilli 35 Updated +Created

There are unlisted articles, also show them or only show them.