Resistance is a fundamental concept in Ohm's Law. It is the property of a material to impede the flow of electric current. Resistance is measured in ohms (Ω) and is denoted by the symbol R. Understanding resistance is crucial in analyzing and designing electrical circuits.

When a voltage is applied across a material, such as a wire or a resistor, the flow of electric current is determined by the resistance of the material. Resistance can be thought of as an obstacle that hinders the movement of electrons. The greater the resistance, the more difficult it is for current to flow.

For example, consider a wire with a resistance of 2 ohms. If a voltage of 5 volts is applied across the wire using a power source, Ohm's Law can be used to determine the current. Using the formula I = V/R, where V is the voltage and R is the resistance, we find that the current flowing through the wire would be 2.5 amperes (A). This means that for every second, 2.5 coulombs of charge will move through the wire.

Resistance can also depend on the physical properties of materials, such as length, cross-sectional area, and temperature. Longer wires or those with smaller cross-sectional areas tend to have higher resistance. Additionally, resistance generally increases with higher temperatures.