Resistor definition

[ "article:topic", "Critical temperature", "ohmic", "semiconductor", "simple circuit", "resisitivity", "authorname:boundless", "high-temperature superconductors", "Superconductivity", "series equivalent resistance", "parallel equivalent resistance", "temperature coefficient of resistivity", "showtoc:no" ] \( \newcommand\) • • • • • • • Ohm’s Law What drives current? We can think of various devices—such as batteries, generators, wall outlets, and so on—which are necessary to maintain a current. All such devices create a potential difference and are loosely referred to as voltage sources. When a voltage source is connected to a conductor, it applies a potential difference V that creates an electric field. The electric field, in turn, exerts force on charges, causing current. The current that flows through most substances is directly proportional to the voltage V applied to it. The German physicist Georg Simon Ohm (1787-1854) was the first to experimentally demonstrate that the current in a metal wire is directly proportional to the voltage applied:\ \(mathrm \). Simple Circuit: A simple electric circuit in which a closed path for current to flow is supplied by conductors (usually metal wires) connecting a load to the terminals of a battery, represented by the red parallel lines. The zigzag symbol represents the single resistor and includes any resistance in the connections to the voltage source. The unit for resistance is the ohm where 1Ω = 1 V/A. We can combine the two rela...

As there are many different types of Resistor available we need to form of resistor colour code system to be able to identify them. Resistors can be used in both electrical and electronic circuits to control the flow of current or to produce a voltage drop in many different ways. But in order to do this the actual resistor needs to have some form of “resistive” or “resistance” value. Resistors are available in a range of different resistance values from fractions of an Ohm ( Ω ) to millions of Ohms. Obviously, it would be impractical to have available resistors of every possible value for example, 1Ω, 2Ω, 3Ω, 4Ω etc, because literally tens of hundreds of thousands, if not tens of millions of different resistors would need to exist to cover all the possible values. Instead, resistors are manufactured in what are called “preferred values” with their resistance value printed onto their body in coloured ink. 4 Coloured Bands The resistance value, tolerance, and wattage rating are generally printed onto the body of the resistor as numbers or letters when the resistors body is big enough to read the print, such as large power resistors. But when the resistor is small such as a 1/4 watt carbon or film type, these specifications must be shown in some other manner as the print would be too small to read. So to overcome this, small resistors use coloured painted bands to indicate both their resistive value and their tolerance with the physical size of the resistor indicating its wat...

Resistors are passive electrical elements. This means they cannot deliver any energy to the circuit, and instead, they receive energy and dissipates it in the form of heat as long as a current flowing through it. Different resistors are used in an electrical and electronic circuit to limit the current flow or produce According to What Does a Resistor do? In an electrical and electronic circuit, resistors are used to limit and regulate current flow, divide voltages, adjust signal levels, bias active elements, etc. For example, many resistors are connected in series used to limit the current flowing through the Protect Against Voltage Spikes A . Resistors are also used to protect LED lights against voltage spikes. LED lights are sensitive to high electrical current, and hence they will get damaged if a resistor is not used to control the flow of electrical current through the LED. Provide Proper Voltage By Creating Voltage Drop Each element in an electrical circuit, like a light or a switch, requires a specific voltage. For that, resistors are used to provide proper voltage by creating a voltage drop across elements. What is Electrical Resistance Measured in (Resistor Units)? The In SI system, an ohm is equal to a 1 volt per ampere. Thus, Therefore, the resistor is also measured in volt per ampere. Resistors are manufactured and specified over a wide range of values. Hence, the derived units of resistors are made according to their values such as milliohm (1 mΩ = 10 -3 Ω), k...

An electronic component that resists the flow of current in an electronic circuit. Resistors are often made out of chunks of carbon or thin films of carbon or other resistive materials. They can also be made of wires wound around a cylinder. The common resistor is a two-wire package with a fixed resistance measured in ohms; however, different types of resistors are adjustable by the circuit designer or the user (see Discrete or IC Discrete resistors are individual packages. On a circuit board, discrete axial resistors are commonly used with their two wires soldered into the holes of the board. Generally smaller than axial resistors, discrete surface-mounted resistors are soldered on top of the board. In addition, resistors are built into microprocessors and other integrated circuits (ICs), but they use semiconductor structures for their fabrication in a manner similar to transistors and PN junctions. See Resistors There are a wide variety of resistors in use. The chip in the center is a reminder that resistive elements are also used in integrated circuits. Axial Resistors Axial resistors are discrete components with wire leads that are soldered to other components or to the circuit board. This type of resistor is easily identified by its color bands, which indicate its resistance and tolerance (see example below). Orange-Orange-Yellow-Gold The color bands on these resistors are interpreted as 3-3-0000-5%, which means 330,000 ohm resistors, plus or minus 5%. Surface Mount R...

Contents • • • • • • What is a Shunt Resistor? A shunt resistor (or shunt) is defined as a device that creates a low resistance path to force most of the Shunt resistors are commonly used in current measuring devices called “ammeters”. In an ammeter, the shunt resistance is connected in parallel. An ammeter is connected in series with a device or circuit. How Does a Shunt Resistor Work? A shunt resistor has a low resistance. It provides a low resistance path to current, and it is connected in parallel with a current measuring device. The shunt resistor uses ohm’s law to measure the current. The resistance of the shunt resistor is known. And it is connected in parallel with the ammeter. So, the voltage is the same. Hence, if we measure the voltage across a shunt resistance, we can measure the current passing through the device by the equation below of ohm’s law. Using a Shunt Resistor to Measure Current Where N is a multiplying power of shunt. How to Build a Shunt Resistor The shunt resister can be built with very thin copper wires. The length and size of the shunt resister depend on the resistance you require. The resistance of the shunt resistor will decide the range of the ammeter. If you use 10 AWG (2.59 mm diameter) copper wire, the resistance of this wire is 0.9989 ohms per 1000 feet. This resistance may vary according to the quality of a wire. Hence, make sure of the resistance before using it. To calculate the required length of wire for a particular value of shunt ...

What is a Variable Resistor? A variable resistor is a resistor of which the electric resistance value can be adjusted. A variable resistor is in essence an electro-mechanical transducer and normally works by sliding a contact (wiper) over a resistive element. When a variable resistor is used as a potential divider by using 3 terminals it is called a Variable Resistor Definition A resistor of which the ohmic resistance value can be adjusted. Either mechanically (potentiometer, rheostat) or electronically (digital potentiometer). Types of Variable Resistors Potentiometer The Rheostat Digital resistor A 2C or by simple up/down signals. Symbols for Variable Resistors The following figure provides the IEC standard symbols for three types of variable resistors. Potentiometer symbol Rheostat symbol Preset resistor symbol

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