In physics and electrical engineeringa conductor is an object or type of material that allows the flow of charge electrical current in one or more directions. Materials made of metal are common electrical conductors. Electrical current is generated by the flow of negatively charged electrons, positively charged holes, and positive or negative ions in some cases.

In order for current to flow, it is not necessary for one charged particle to travel from the machine producing the current to that consuming it. Instead, the charged particle simply needs to nudge its neighbor a finite amount who will nudge its neighbor and on and on until a particle is nudged into the consumer, thus powering the machine. Essentially what is occurring is a long chain of momentum transfer between mobile charge carriers; the Drude model of conduction describes this process more rigorously.

This momentum transfer model makes metal an ideal choice for a conductor; metals, characteristically, possess a delocalized sea of electrons which gives the electrons enough mobility to collide and thus effect a momentum transfer. As discussed above, electrons are the primary mover in metals; however, other devices such as the cationic electrolyte s of a batteryor the mobile protons of the proton conductor of a fuel cell rely on positive charge carriers.

Insulators are non-conducting materials with few mobile charges that support only insignificant electric currents. The resistance of a given conductor depends on the material it is made of, and on its dimensions. For a given material, the resistance is inversely proportional to the cross-sectional area. Also, for a given material, the resistance is proportional to the length; for example, a long copper wire has higher resistance than an otherwise-identical short copper wire.

The resistance R and conductance G of a conductor of uniform cross section, therefore, can be computed as . The resistivity and conductivity are proportionality constants, and therefore depend only on the material the wire is made of, not the geometry of the wire. Resistivity is a measure of the material's ability to oppose electric current.

This formula is not exact: It assumes the current density is totally uniform in the conductor, which is not always true in practical situation.

However, this formula still provides a good approximation for long thin conductors such as wires. Another situation this formula is not exact for is with alternating current ACbecause the skin effect inhibits current flow near the center of the conductor.

Then, the geometrical cross-section is different from the effective cross-section in which current actually flows, so the resistance is higher than expected. Similarly, if two conductors are near each other carrying AC current, their resistances increase due to the proximity effect. At commercial power frequencythese effects are significant for large conductors carrying large currents, such as busbars in an electrical substation or large power cables carrying more than a few hundred amperes.

Aside from the geometry of the wire, temperature also has a significant effect on the efficacy of conductors. Temperature affects conductors in two main ways, the first is that materials may expand under the application of heat. The amount that the material will expand is governed by the thermal expansion coefficient specific to the material.

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Such an expansion or contraction will change the geometry of the conductor and therefore its characteristic resistance. An increase in temperature will also increase the number of phonons generated within the material. A phonon is essentially a lattice vibration, or rather a small, harmonic kinetic movement of the atoms of the material. Much like the shaking of a pinball machine, phonons serve to disrupt the path of electrons, causing them to scatter.Related to conductance: Thermal conductanceequivalent conductanceElectrical conductancespecific conductance.

Symbol G A measure of a material's ability to conduct electric charge; the reciprocal of the resistance. It is measured in reciprocal ohms, mhos, or siemens. Symbol: G. A measure of the ability of a material to carry an electric charge. Switch to new thesaurus.

Mentioned in? References in periodicals archive? Comparing physiological and environmental temperature data for bird and mammal species, the scientists demonstrated that birds and mammals have adapted to geographic variation in environmental temperature by concerted changes in both metabolic heat production and thermal conductance. Multiple Avenues to Adapt to Temperature.

Stomatal conductance is potentially one of the most significant physiological characters to improve adaptation to drought for selecting a particular pattern of stomatal behavior Blumet al.

Increasing stomatal density improves maximum potential conductance Franks et al. As can be seen in acetonitrile solvent, addition of the ligand to the metal ions solutions cause a continuous increase in molar conductance of the solutions.

The conductance fluctuations are observed, and they decrease as [T. L] increase from [T.

The ratio of different layers to their respective resistivities is known as longitudinal conductance. The properties of the conducting layers is determined interms of the longitudinal conductance and resistive layer by transverse resistance Yungul, ; Nwanko et al. The study of aquifers potential and contamination based on geoelectric technique and chemical analysis in Mirpur Azad Jammu and Kashmir, Pakistan. The team concluded that eye tracking is more dependable than skin conductance as a distinguisher between someone one who suffers from social anxiety and someone who does not.

The MDTS algorithm goes through an iterative learning process that computes which of all possible positions is best for placing silicon or germanium in order to achieve the desired degree of thermal conductance. The game algorithm that could improve materials design. During the sensing time period, there are two distinct phases of the sensor's electrical conductance behavior: a "deadband" phase when the sensor's conductance does not noticeably change even though the sensor surface is collecting soot, and an "active" phase when the sensor's conductance increases noticeably in response to increasing soot loading.

Skin conductance and heart rate in women with premenstrual syndrome. Galvanic skin resistance in different phases of menstrual cycle in acne vulgaris. The effects of neuronal noise added to the stimulus, the conductanceand the modulation function are investigated, respectively, based on a circadian input skewed in sine function proposed by Daan et al.

Dictionary browser? Full browser?A measure of the ability of a substance to allow electric current to pass through in relation to the applied voltage E.

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Conductance is the reciprocal of resistance Ras measured in ohms. Conductance is measured in mhos, which is ohms spelled backwards. Isn't that clever? Sentences Sentence examples. By continuing, you agree to our Terms of Use and Privacy Policy. Please set a username for yourself.

Angular 4 keep data after refresh Thermal conductance. A measure of the ability of a material to carry electric current. For alternating current, conductance is called admittance.

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Conductance is measured in mhos. See more at admittance See thermal conductance. Noun uncountable physics A measure of the ability of a body to conduct electricity ; the reciprocal of its resistance. SI unit: siemen S. English Wiktionary. Home Dictionary Definitions conductance.

Sentence Examples. Also Mentioned In. Join YourDictionary today.Conductance is a measure of how well an artefact such as an electrical component, not a material, such as iron carries an electric current. Resistance is a measure of how well an artefact resists an electric current. Conductance is measured in Siemens usually abbreviated S and, in formulae, is represented by the letter G.

Ohm's Law states that the potential difference across an artefact constructed from Ohmic conductors i. As a formula:. This formula can be rearranged to give a formula which can be used to calculate the resistance of an artefact:. From Ohm's Law, we can see that potential difference is directly proportional to current, provided resistance is constant. This is because two variables let us call them x and y are considered directly proportional to one another if:. As a result, if potential difference is plotted against current on a graph, it will give a straight line with a positive gradient which passes through the origin. The gradient will equal the resistance. In a series circuit for example, a row of resistors connected to each otherthe resistances of the resistors add up to give the total resistance. Since conductance is the reciprocal of resistance, the reciprocals of the conductances add up to give the reciprocal of the total conductance. In a parallel circuit, the conductances of the components on each branch add up to give the total conductance. Similar to series circuits, the reciprocals of the total resistances of each branch add up to give the reciprocal of the total resistance of the circuit.

When considering circuits which are a combination of series and parallel circuits, consider each branch as a separate component, and work out its total resistance or conductance before finishing the process as normal.

The potential difference across a resistor is 4V, and the current is 10A. What is the resistance of the resistor? A conductor has a conductance of 2S, and the potential difference across it is 0. How much current is flowing through it? A graph is drawn of potential difference across an Ohmic conductor, and current.

What is the conductance of the conductor? On another graph of potential difference and current, the graph curves so that the gradient increases as current increases.

## Electrical resistance and conductance

What can you say about the resistor? What is the total resistance across all three resistors?

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What is the total resistance of both branches of the parallel circuit? What is the total conductance of the circuit now? Worked Solutions. From Wikibooks, open books for an open world. Namespaces Book Discussion.Conduction refers to the transfer of energy through the movement of particles that are in contact with each other. In physics, the word "conduction" is used to describe three different types of behavior, which are defined by the type of energy being transferred:.

This is similar to the explanation of heat by the kinetic theory of gasesthough the transfer of heat within a gas or liquid is usually referred to as convection. The rate of heat transfer over time is called the heat currentand it is determined by the thermal conductivity of the material, a quantity that indicates the ease with which heat is conducted within the material. For example, if an iron bar is heated at one end, as shown in the image above, the heat is understood physically as the vibration of the individual iron atoms within the bars.

The atoms on the cooler side of the bar vibrate with less energy. As the energetic particles vibrate, they come into contact with adjacent iron atoms and impart some of their energy to those other iron atoms. Over time, the hot end of the bar loses energy and the cool end of the bar gains energy, until the entire bar is the same temperature. This is a state known as thermal equilibrium. In considering heat transfer, though, the above example is missing one important point: the iron bar is not an isolated system.

In other words, not all of the energy from the heated iron atom is transferred by conduction into the adjacent iron atoms. Unless it's being held suspended by an insulator in a vacuum chamber, the iron bar is also in physical contact with a table or anvil or another object, and it is also in contact with the air around it.

As air particles come into contact with the bar, they too will gain energy and carry it away from the bar though slowly, because the thermal conductivity of unmoving air is very small. The bar is also so hot that it is glowing, which means that it is radiating some of its heat energy in the form of light.

This is another way in which the vibrating atoms are losing energy. If left alone, the bar will eventually cool down and reach thermal equilibrium with the surrounding air.

Electrical conduction happens when a material allows an electrical current to pass through it. Whether this is possible depends on the physical structure of how the electrons are bound within the material and how easily the atoms can release one or more of their outer electrons to neighboring atoms.

The degree to which a material inhibits the conduction of an electrical current is called the material's electrical resistance.

Certain materials, when cooled to nearly absolute zerolose all electrical resistance and allow electrical current to flow through them with no loss of energy.

These materials are called superconductors. Sound is physically created by vibrations, so it is perhaps the most obvious example of conduction. A sound causes the atoms within a material, liquid, or gas to vibrate and transmit, or conduct, the sound through the material. A sonic insulator is a material whose individual atoms do not easily vibrate, making it ideal for use in soundproofing.

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Conductance and Conductivity - Current Electricity - Diploma Physics 1

The conductance of a component tells you how good a conductor it is. The higher the conductance the better the component is at conducting. Conductance is just the inverse of resistance. It used to be called the mho, which is just ohm written backwards.

When we first learn about electricity we tend to talk about conductors and insulators. The idea of conductance fits in quite nicely with this.

## Conductivity

If something's a good conductor it has a high conductance. The idea of resistance is often imagined as something external resisting the current somehow. It's much more natural to think of some things just being good conductors, rather than being the victim of this external effect called resistance. Remember also that batteries are constant voltage providers if you ignore internal resistance. That depends on what's in the circuit.

In other words you're asking 'I wonder what voltage I need for a current of 1 amp to flow through my component? You don't just go around changing it. This makes much more sense because you typically specify the voltage by for example connecting a component to a particular battery and measure the current you get.

Conductivity is the inverse of resistivity. The unit of conductivity is the siemens per metre see below. Again it's a material property rather than a component property.

So you talk about the conductivity of copper but the conductance of this piece of copper wire. A piece of wire has a high conductance if it's short and fat. So the conductance of a piece of wire depends on. Conductance and conductivity The definition of conductance The conductance of a component tells you how good a conductor it is.What is Resistance of a Conductor The movement of electron gives rise to the flow of current through metals.

The moving electrons collide with each other as well as with the positive ions present in the metallic conductor. These collisions tend to slow down the speed of the electrons and hence oppose the flow of electric current.

The property of a conductor by virtue of which it opposes the flow of electric current through it is called its resistance. Table summarises the factors affecting resistance and their relationships. Aim: To investigate the factors affecting resistance. Problem: What are the factors affecting the resistance of a conducting wire? Materials: 50 cm eureka wire s. Hypothesis: For a fixed length and thickness of a conducting wire used, its resistance is affected by the type of material.

Variables: a Manipulated variable: Types of material of the wire b Responding variable: Resistance, R c Fixed variable: Thickness, length and temperature of wire Operational Definition: The resistance, R of a conducting wire is given by the ratio of the reading of the voltmeter to the reading of the ammeter. Hypothesis: The resistance of a conducting wire increases with its length.

Variables: a Manipulated variable: Length of wire, l b Responding variable: Resistance, R c Fixed variable: Thickness, type of wire and temperature of wire Operational Definition: The resistance, R of a conductor is given by the ratio of the reading of the voltmeter to the reading of the ammeter. Conclusion: The resistance, R of a conducting wire is directly proportional to the length of the wire, l.

The hypothesis is accepted. The resistance, R of the wire increases with its length, l. Hypothesis: For a fixed length of a conducting wire, the thicker the wire, the smaller the resistance. Variables: a Manipulated variable: Thickness of wire b Responding variable: Resistance, R c Fixed variable: Type, length and temperature of wire Operational Definition: a The thickness of a conductor is determined by the value of its s. Conclusion: The resistance, R of a wire is inversely proportional to its cross-sectional area, A.

The thicker the wire, the lower the resistance. Hypothesis: When the temperature of the filament bulb increases, its resistance increases. Variables: a Manipulated variable: Temperature of the filament b Responding variable: Resistance, R c Fixed variable: Type of bulb used Operational Definition: a The temperature of the filament is determined by the brightness of the bulb. Discussion: The brightness of the bulb corresponds to the temperature of the bulb. The brighter the bulb, the higher its temperature.

Conclusion: The resistance of a filament increases as its temperature increases. What is the definition of resistance in physics?

### conductance

Different conductors have different resistance to current flow. Resistance is denoted by the letter R. The resistance, R of a conductor is defined as the ratio of potential difference, V across the conductor to the current, I flowing through it. Thus: The SI unit of resistance is ohm.