# Resistance in a conductor

When cooled to extremely low temperatures, some conductors have zero resistance. And on the other hand, when two or more resistances are connected between the same two points, they are said to be connected in parallel.

## Resistance of copper wire

The obstruction posed in the way of current carrying particles by fixed particles creates resistance in an electric circuit. And the current flowing through all the individual parallel resistances, taken together, is equal to the current flowing in the circuit as a whole. In the same way, a long, thin copper wire has higher resistance lower conductance than a short, thick copper wire. But there may be an equally large water pressure below the pipe, which tries to push water back up through the pipe. Pushing electric current through a large resistance is like pushing water through a pipe clogged with hair: It requires a larger push electromotive force to drive the same flow electric current. Resistances in Series: The combined resistance of any number of resistances connected in series is equal to the sum of the individual resistances. With increasing temperature, the resistance of the wire increases as collisions within the wire increase and "slow" the flow of current. An ohmmeter could be used to verify this value. Silver metal, Copper and Aluminium etc.

The dissipation of electric energy in the form of heat, even though small, affects the amount of electromotive forceor driving voltage, required to produce a given current through the circuit.

For a given material, the resistance is inversely proportional to the cross-sectional area; for example, a thick copper wire has lower resistance than an otherwise-identical thin copper wire. Potential Difference across the ends of the conductor and Resistance of the conductor.

The resistance of a wire is directly proportional to its length and inversely proportional to its cross-sectional area. An ohmmeter could be used to verify this value. See resistivity. Examples include diodes and fluorescent lamps.

## Resistivity

It allows electricity to flow through it easily. If this resistance is just right, the current flowing through the wire is slowed just enough, without stopping as a result of too much resistance, that the filament heats up to the point that it glows. Pushing electric current through a large resistance is like pushing water through a pipe clogged with hair: It requires a larger push electromotive force to drive the same flow electric current. Main article: Ohm's law The current-voltage characteristics of four devices: Two resistors , a diode , and a battery. So, it is necessary to combine two or more resistances to get the required current in the electrical circuits. Disadvantages of Series circuits for domestic Wiring The arrangement of lights and various other electrical appliances in series circuit is not used in domestic wiring because i If one electrical appliance stops working due to some defect, then all other appliances also stop working. Learn More in these related Britannica articles:.

The voltage drop i. Since conductors typically display an increased resistivity with temperature increase, they have a positive temperature coefficient.

It allows electricity to flow through it easily. We also should keep in mind that when a number of resistances are connected in parallel, then the potential difference across each resistance is the same which is equal to the voltage of the battery applied.

Resistance also depends on the material of the conductor. Here, the resistivity and conductivity are proportionality constants.

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