For an explanation, see the main splats page
The principles of electronics
- A capacitor can store a static charge. A Leyden jar was an early form of capacitor, charged by electrostatic means. The unit of capacitance is the farad.
- Conductors may be in a parallel circuit or in a series circuit. At the junction of any circuit, all electric currents must obey Kirchhoff's laws.
- Resistance is measured in ohms, conductance is measured in mhos, each refers to a conductor's capacity to allow electrons to pass through it.
- A potentiometer (or a rheostat) has a variable resistance because a slider can tap in at various points on what is generally a uniform resistor.
- A light dependent resistor can be used to measure light intensity, because the resistance it causes to a current is proportional to the light falling on it.
- A light dependent resistor can be used to measure light intensity in a uniform way, since the resistance varies with the intensity of the incident light.
- A reed switch uses a magnetic effect, changing from one state (with the switch open or closed) to the other when a magnet is moved near it or away from it.
- An image intensifier is a device that allows us to see in what is effectively the dark, by taking the few available photons and amplifying them.
- Electrons can flow through a vacuum, and this is the basis of the thermionic valve, where electrons are 'boiled off' a hot cathode and then travel to an anode.
- Thomas Edison made just one real scientific discovery, the 'Edison effect', which is the key to the thermionic valve. He patented it, but never used it.
- An integrated circuit or chip contains many separate semiconductor devices, all of them incorporated into a single unit, made in a single process.
- Modern electronics relies on semiconductor devices: a diode only allows current to flow in one direction, a transistor can act as a switch or an amplifier.
- The strength of a signal may be increased with an amplifier, a circuit designed for that purpose, and using either thermionic valves or transistors.
- A diode only allows current to pass in one direction, and a set of diodes may be arranged to make a full-wave rectifier, as in a conventional power pack.
- In 1947, the transistor effect was noted, and by 1948, William Shockley, Walter Brattain, and John Bardeen had made and proven the first working transistor.
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