Electrical4U 
A DC generator is defined as an electrical device that converts mechanical energy into direct current (DC) electricity. It works on the principle of electromagnetic induction, where an electric potential difference is created across a conductor when it cuts through a magnetic field, causing a current to flow if connected to a closed circuit. A … Read more
What is a Variable Resistor? An adjustable variable resistor is a resistor whose electrical resistance can be set mechanically or electronically. The set resistance can control current, divide a voltage or set a circuit parameter under Ohm’s Law. This article focuses on adjustable resistors with a resistive element and wiper. In a mechanical unit, the … Read more
Dielectric materials are electrical insulators that store electric charge and support electrostatic fields. They appear inside capacitors, transformers, antennas, sensors and optical fibers, where their ability to be polarized rather than to conduct does the useful work. What is a dielectric material? A dielectric material has low electrical conductivity and high electric susceptibility. Conductivity measures … Read more
A light-dependent resistor (LDR) is a two-terminal photoconductive component. Its resistance normally falls as incident optical power increases within the device’s spectral response. Commercial parts can show megohms in darkness and much low resistance under their specified illumination, but the actual values depend on part, spectrum, illuminance, temperature and adaptation time. LDRs suit simple light … Read more
Electromagnetic theory describes electric charge, current and the coupled electric and magnetic fields. Together with the Lorentz force law, it predicts forces on charges and the propagation of electromagnetic radiation, including light and X-rays. Maxwell’s four field equations relate charge and current to electric and magnetic fields. They include Gauss’s laws, Faraday’s law and the … Read more
A parallel plate capacitor has two facing conductors separated by an insulating gap. Opposite free charges create an electric field in the gap and store electrostatic energy. A voltage source can charge the plates, but the capacitor can remain charged after the source is removed. The gap may contain vacuum, gas or a dielectric material. … Read more
A vacuum diode is a two-electrode tube that conducts mainly in one direction through an evacuated envelope. Its heated cathode emits electrons, and a positively biased anode collects them. Electron motion is from cathode to anode, while conventional electric current is defined in the opposite direction. A cathode may be a directly heated filament or … Read more
Ionization is a fundamental concept in chemistry and physics that describes the transformation of electrically neutral atoms or molecules into electrically charged ones. Ionization occurs when an atom or molecule gains or loses one or more electrons, resulting in a positive or negative charge. The charged atom or molecule is called an ion. Ionization can … Read more
An optoisolator is an electronic component that transfers a signal between two circuits with no direct conductive connection. Light carries the signal across an insulating barrier, so the circuits can operate at different voltages or ground potentials. This galvanic separation can protect low-voltage electronics and reduce ground-loop noise when the device is selected and used within its … Read more
A standalone solar photovoltaic (PV) system supplies local loads without relying on a utility grid connection. It can power lighting, water pumps, ventilation, communications and other equipment at remote sites. Depending on when and how the load operates, the system may connect PV modules directly to a DC load, store energy in batteries or combine … Read more