Electricity Basics: Resistance, Inductance and Capacitance.

Pedro_P

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Several examples of resistors. Resistors convert energy to heat and dissipate it.
Credit: Peter Mathys, University of Colorado
▼ Electronic circuits are integral parts of nearly all the technological advances being made in our lives today. Television, radio, phones and computers immediately come to mind, but electronics are also used in automobiles, kitchen appliances, medical equipment and industrial controls. At the heart of these devices are active components, or components of the circuit that electronically control electron flow, like semiconductors. However, these devices could not function without much simpler, passive components that predate semiconductors by many decades. Unlike active components, passive components, such as resistors, capacitors and inductors, can't control the electron flow with electronic signals.
• Resistance
As its name implies, a resistor is an electronic component that resists the flow of electric  currentin a circuit.
In metals such as silveror copper, which have high electrical conductivity and therefore low resistivity, electrons are able to skip freely from one atomto the next, with little resistance.
The electrical resistance of a circuit component is defined as the ratio of the applied voltage to the electric current that flows through it, according to HyperPhysics, a physics resource website hosted by the department of physics and astronomy at Georgia State University. The standard unit for resistance is the ohm, which is named after German physicist Georg Simon Ohm. It is defined as the resistance in a circuit with a current of 1 ampere at 1 volt. Resistance can be calculated using Ohm's law, which states that resistance equals voltage divided by current, or R = V/I (more commonly written as V = IR), where R is resistance, V is voltage and I is current.
Resistors are generally classified as either fixed or variable. Fixed-value resistors are simple passive components that always have the same resistance within their prescribed current and voltage limits. They are available in a wide range of resistance values, from less than 1 ohm to several million ohms.
Variable resistors are simple electromechanical devices, such as volume controls and dimmer switches, which change the effective length or effective temperature of a resistor when you turn a knob or move a slide control.

An example of an inductor made from a copper wire installed on a circuit board.
Credit: Shutterstock
• Inductance
An inductor is an electronic component consisting of a coil of wire with an electric current running through it, creating a magnetic field. The unit for inductance is the henry (H), named after Joseph Henry, an American physicist who discovered inductance independently at about the same time as English physicist Michael Faraday. One henry is the amount of inductance that is required to induce 1 volt of electromotive force (the electrical pressure from an energy source) when the current is changing at 1 ampere per second.
One important application of inductors in active circuits is that they tend to block high-frequency signals while letting lower-frequency oscillations pass. Note that this is the opposite function of capacitors. Combining the two components in a circuit can selectively filter or generate oscillations of almost any desired frequency.
With the advent of integrated circuits, such as microchips, inductors are becoming less common, because 3D coils are extremely difficult to fabricate in 2D printed circuits. For this reason, microcircuits are designed without inductors and use capacitors instead to achieve essentially the same results, according to Michael Dubson, a professor of physics at the University of Colorado Boulder.

Several examples of capacitors. Capacitors store electric charge.
Credit: Peter Mathys, University of Colorado
• Capacitance (▪ ▪ ▪)

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ssangra

Do u have any literature on the rodin coils ?

Pedro_P

Hi... You can request a recommendation about it here: General Thread of Requests for «Reading Recommendations»

dushazmi

good information, explanation crisp.