Electrical resistance is a fundamental property of materials that describes their ability to resist the flow of electric current. When an electric current passes through a material, it encounters resistance, which converts some of the electrical energy into heat. This concept is based on Ohm's Law, which states that the current (I) flowing through a conductor is directly proportional to the voltage (V) applied across it and inversely proportional to the resistance (R) of the material:
Here, the unit of electrical resistance is the ohm, represented by the symbol "Ω." One ohm is defined as the resistance through which one volt of potential difference will produce a current of one ampere.
The resistance of a material depends on several factors, including its physical dimensions, the material's resistivity (a property that quantifies the resistance of a specific material), and the temperature. Different materials have different resistivities, and some materials are better conductors (lower resistance) of electricity than others.
Materials that have low resistance are known as conductors, and they allow electric current to flow easily. Copper and aluminum are examples of good conductors commonly used in electrical wiring. In contrast, materials with high resistance are known as insulators and inhibit the flow of current. Examples of insulators include rubber and plastic.
Electrical resistance is a crucial concept in designing electrical circuits and understanding how electricity behaves in various devices and systems. It is also the basis for important devices like resistors, which are used to control current flow in circuits, and heating elements, which utilize the resistance to generate heat.