Spacial coherence by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Spectral coherence by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Spectophotometry by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Video 1.
Donated Eskalab Spectrophotometer by CuriousMarc
. Source.
Single-mode and multi-mode optical fiber by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
From a practical point of view single-mode:
As such, typical applications are:
From a mathematical point of view:
Saturation magnetisation by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Ethernet over fiber by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Magnetic hysteresis by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
To understand the graph, first learn/remember the difference between the magnetic B and H field.
The interest of the magnetic hysteresis graph is that it serves as an important characterization of a :
This curve will also tell you how many turns of the coil will be needed to reach the required field.
Video 1.
Measurement of B-H characteristic
. Source.
1989. 1989 and they were making such awesome materials. It is hard to understand why university still exists given this.
Shows how you can obtain the magnetic hysteresis curve with an AC source plus an oscilloscope in XY mode. youtu.be/pXukVix5Pcw?t=193 clearly shows the measurement circuit.
Video 2.
Magnetic hysteresis experiment by UNSW Physics.
Source.
2020, thanks COVID-19. Like other UNSW Physics YouTube channel videos, the experimental setup could be made clearer with diagrams.
But this video does have one merit: it shows that the hysteresis plot can be obtained directly with the oscilloscope XY mode by using an AC source. The Y axis is just a measure of the total magnetic field induced by the primary coil + the magnetization of the material itself.
Ice Ih by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Early models were heavy and not practical for people to carry them, so the main niche they initially filled was being carried in motor vehicles, notably trucks where drivers are commercially driving all day long.
It also helps in the case of trucks that you only need to cover a one-dimensional region of the main roads.
For example, this niche was the original entry point of companies such as:
History of mobile phone by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Ethernet physical layer by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Lifting electromagnet by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Video 1.
Easy-to-Build Electromagnet lifts over 50 lbs by Dorian McIntire
. Source. Fun, but zero reproducibility.
Solenoid by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16
Solenoid means "tubular" in Greek.
Solenoids are simpler to build as they don't require insulated wire as in modern electrical cable because as the electromagnetic coils don't touch one another.
As such it is perhaps the reason why some early electromagnetism experiments were carried out with solenoids, which André-Marie Ampère named in 1823.
But the downside of this is that the magnetic field they can generate is less strong.
Figure 1.
Illustration of a solenoid
.
Figure 2.
Magnetic field lines around a solenoid cross-section
. TODO accurate simulation or not?
Oscilloscope XY mode by Ciro Santilli 37 Created 2024-06-26 Updated 2025-07-16

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