What is Electrical Resistance? Definition and Unit of Resistance
When an electric voltage is applied to a material, electrons begin to flow through it. The amount of electrons that pass through the material varies depending on its electrical conductivity. Materials that are good conductors, like metals, offer less resistance to the flow of electrons than insulators. In metals, the electrons are loosely bound and can be easily released with a low voltage. However, in insulators, the electrons are tightly bound and require a lot of energy to be released.
When a voltage is applied to a metal, the free electrons within it begin to move from areas of lower potential to areas of higher potential. However, during this motion, electrons collide with each other and with atoms within the substance, causing hindrance in the free movement of electrons. This hindrance results in resistance to the flow of electrons.
Resistance is a property of a material that opposes the flow of electrons. It is important to note that the flow of current is opposite to the flow of electrons. In simpler terms, we can define resistance as the material’s property that resists the flow of electric current.
Resistance is a measure of a material’s ability to oppose the flow of electric current and is measured in Ohms. The symbol for resistance is denoted by the Greek letter Ω and is named after Georg Simon Ohm, who was a German physicist who formulated Ohm’s law by studying the relationship between voltage, current, and resistance.
Metals such as silver, gold, aluminum, and copper are good conductors of electricity because they offer less resistance. In contrast, insulators such as rubber, paper, and glass are bad conductors of electricity due to their higher resistance. The current flow through a material is inversely proportional to its resistance. The lower the resistance, the higher the current flow, and vice versa.
Unit of Resistance
The unit of resistance is Ohm(Ω). According to Ohm’s Law;
R = V/I
When 1 volt is applied to the circuit, it causes 1-ampere current to flow in the circuit, then the resistance of the circuit is 1Ω.
R = V/I = 1/1 = 1Ω
The resistance can also be expressed in the lower and bigger units of Ohm. These are milli-ohm,micro-ohm,kilo-ohm,mega-ohm,giga-ohm and tera-ohm.
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