Before we know what is resistance, it is necessary to understand about current. Actually, the flow of current in a material consists of a movement of electrons. Moreover, the movement of electrons is in one direction. In many materials, free electrons move randomly within the system. In addition, When electrons move randomly then there is no current flow. This is because the number of moving electrons in one direction is equal to the number of moving electrons in the other direction. Current flow only when a potential causes a drift in a particular direction.
What is resistance
Resistance is the hurdle to the flow of electrons in a material. Furthermore, a potential difference in the conductor encourages the electrons to flow. But the resistance discourages it. In other words, it is a measure of the opposition to current flow in an electrical circuit.
The unit of resistance is ohms. Its symbol is a Greek letter. We denote resistance by omega (Ω). Georg Simon Ohm is a German physicist. He studied the relationship between voltage, current, and resistance. He is credited for his formula which is ohms law.
We get it by,
V ∝ I V = IR
V = is the potential difference that is measured across the conductor ( volts )
I = is the current passing through the conductor ( ampere )
R = is the constant of proportionality that is known as resistance ( ohms)
When we rearrange the above equation it becomes,
R = V/I
According to its units,
Ohm = Volt / Ampere
Electric current flows more easily through some components than others. We measure this by calculating how much the flow of electric charges is minimal within the circuit.
When an electric current of one ampere passes through a component. This component has a potential difference of one volt. Then the resistance of this component is one ohm.