The Resistivity of Various Materials A material with low resistivity means it has low resistance and thus the electrons flow smoothly through the material. For example, Copper and Aluminium have low resistivity. Good conductors have less resistivity. Insulators have a high resistivity.

A low resistivity indicates a wire that readily allows the movement of electrical charge. Copper has a resistivity of 0.0171 Ohm · mm²/m and is, therefore, one of the best conductors for electric current (slightly behind pure silver).

Examples: silver, copper, gold and aluminum. Insulators: Materials that present high resistance and restrict the flow of electrons. Examples: Rubber, paper, glass, wood and plastic.

silver

copper

1. Decreasing the resistivity of the material the wire is composed of will increase the resistance of the wire. 2. Increasing the length of the wire will increase the resistance of the wire.

Set your multimeter to the highest resistance range available. The resistance function is usually denoted by the unit symbol for resistance: the Greek letter omega (Ω), or sometimes by the word “ohms.” Touch the two test probes of your meter together. When you do, the meter should register 0 ohms of resistance.

The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance. The resistance of a long wire is greater than the resistance of a short wire because electrons collide with more ions as they pass through.

Resistance is measured in units called ohms, represented by the Greek letter omega (Ω). The standard definition of one ohm is simple: It’s the amount of resistance required to allow one ampere of current to flow when one volt of potential is applied to the circuit.

Typically, good wire connections have a resistance of less than 10 Ω (often only a fraction of an ohm), and isolated conductors offer a resistance of 1 MΩ or greater (typically tens of megohms, depending on humidity).

Common Wire Gauges

If there really were no resistance in the circuit, the electrons would go around the circuit, and arrive back at the beginning of the circuit with as much energy as the potential difference (the voltage). That final energy is usually what is dissipated as heat or other types of energy by the circuit.

In circuit analysis, a short circuit is defined as a connection between two nodes that forces them to be at the same voltage. In an ‘ideal’ short circuit, this means there is no resistance and thus no voltage drop across the connection. In real circuits, the result is a connection with almost no resistance.

Typically the resistance associated with a short circuit is so low as to be considered zero.

When the resistance in any circuit is equal to zero then the current passing through that circuit will be infinite. We know from Ohm’s law that V=IR. Here, if you consider resistance as zero then the equation becomes V=I(0). …

In the case where there is no resistance, current (once flowing) does not require any voltage to continue flowing. Likewise it doesn’t take any voltage to keep current flowing if there is no resistance. You’re correct that if you have a perfect insulator (R=∞), then any applied voltage will still produce zero current.

Superconductors are materials that carry electrical current with exactly zero electrical resistance. This means you can move electrons through it without losing any energy to heat.

It’s not possible to get a negative resistance with purely passive components. We can see that from thermodynamics. A normal (positive) resistor puts out heat to the surroundings – voltage times current gives us the power dissipated. A negative resistor would need to suck in heat and turn it to electrical energy.