Resistance
Resistance is the property of a material or component that opposes the flow of electric current through it. It is measured in Ohms and denoted by the symbol “Ω”.
Resistance arises due to the interactions between electrons and the atoms or molecules that make up the material. When an electric current flows through a material, the electrons collide with these atoms or molecules, causing the electrons to lose energy and reducing the flow of current.
The resistance of a material depends on several factors, including its length, cross-sectional area, and the material’s resistivity, which is a measure of how strongly the material opposes the flow of current. Some materials, such as metals, have low resistance and are good conductors of electricity, while other materials, such as rubber or glass, have high resistance and are insulators.
Resistance – Hydraulic Analogy
The hydraulic analogy, or the electric-fluid analogy, is a widely used analogy between hydraulics and electricity, which is a useful tool for teaching and for those who are struggling to understand how circuits work. it can also be applied to heat transfer problems.
Since electric current is invisible and the processes in play in electronics are often difficult to demonstrate, the various electronic components are represented by hydraulic equivalents. The relationship between voltage and current is defined (in ohmic devices like resistors) by Ohm’s law. Ohm’s Law is analogous to the Hagen–Poiseuille equation, as both are linear models relating flux and potential in their respective systems.
Electricity (as well as heat) was originally understood to be a kind of fluid, and the names of certain electric quantities (such as current) are derived from hydraulic equivalents.
- Voltage is like the pressure difference that pushes water through the hose. It is measured in volts (V). This model assumes that the water is flowing horizontally so that the force of gravity can be ignored.
- Current is equivalent to a hydraulic volume flow rate; that is, the volumetric quantity of flowing water over time. Usually measured in amperes. The wider pipe is, the more water will flow through. It is measured in amps (I or A).
- Resistance is like pipe diameter or obstacles in the hose that slow down the water flow. It is measured in ohms (Ω). In hydraulics, resistance is associated with the pressure loss coefficient.
- Resistors are comparable to a section of the pipe network where the radius of the pipe is constricted, restricting the rate of fluid flow in that region, the same way that a resistor limits current.
