What is Electrical Resistance?

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What is Electrical Resistance?

Electricity Resistance Company. Electricity Resistance cannot move completely smoothly in an electrical conductor (except superconductors, but this is a physical special case). You can do that on the basis of a In a simplified way, imagine that the electrons on their way through the metal lattice collide with the positively charged ions and release some of their kinetic energy to them. Therefore, to move electrons through a conductor, one must expend some power. The external energy supply, which the electrons in the conductor deliver to the metal ions, the metal ions are excited to stronger vibration, whereby the metal is heated.

By providing a variable voltage source with a voltage and current measuring instrument and connecting an electrical conductor to a measuring circuit, you can observe how the current changes as a function of the applied voltage. At zero Volts, no current is expected to flow, but if you slowly increase the voltage, the current will increase as well. The result is the exemplary relationship between voltage and current.

It is interesting to know what the height of the resistance value of an electrical conductor actually depends on. For this you can do the following little experiment: First of all, determine the resistance of a copper wire of a certain length.

Then take a second, completely identical copper wire and connect its beginning with the beginning and its end with the end of the first wire, ie you double the cross section. When determining the resistance of the combination, it will be noted that the resistance drops to exactly half.

This is not really surprising when you consider that the current compared to the single wire, the double conductor cross-section is available. Now, in another experiment, hang the second wire behind the first, resulting in exactly twice as long a lead. The resistance of the two wires connected in series is now twice as high as that of a wire alone.

This, too, is not surprising, because the current must flow first through the first line, which has a certain resistance, and then immediately further through the second, which has the same resistance. If one carries out the test with 3 or 4 identical wires, it is found that the resistance at the three or four times cross section drops to one third or one fourth of the value of a single wire and three or four times the length on the three – or quadruple value increases.

The resistance thus decreases inversely proportional to a cross-sectional increase, while it increases in proportion to the length of a length change. This can be written as follows:

 

Replacing the copper wire with wires of other materials reveals that each material has a different resistivity. The metal with the lowest resistivity is silver, closely followed by copper. The noble gold, however, is a comparatively poor electrical conductor.

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