<p align="right">Last Update: <font color="#4f81bd">July, 27, 2024</font></p> ## BIG IDEA - Resistance quantifies how much a material resists the movement of electric charges. - SI unit is ohm ($\Omega$). >[!note] Definition >Resistance is a measure of the opposition to the flow of electric current through a conductor. One ohm is defined as the resistance between two points of a conductor when a constant potential difference of one volt applied between these points produces a current of one ampere. $1 \Omega \ = \ 1 \frac{V}{A}$ where $V$ stands for volts, $A$ stands for amperes. Resistance in a conductor depends on several factors: - **Material:** Different materials have different resistivities. Conductors (like copper) have low resistance, while insulators (like rubber) have high resistance. - **Length of the Conductor:** Resistance is directly proportional to the length of the conductor. The longer the conductor, the higher the resistance. - **Cross-sectional Area:** Resistance is inversely proportional to the cross-sectional area of the conductor. A thicker wire has less resistance compared to a thinner wire. - **Temperature:** For most conductors, resistance increases with an increase in temperature. However, some materials (like semiconductors) have more complex relationships with temperature. --- Return [[Home|Home]] | [[Notes Vault/Physics Notes Vault/DC Circuits/Electric Circuits|Circuits]] | [[Electric Current]] | [[Voltage]] | [[Resistance]] | [[Resistors]] | [[Notes Vault/Physics Notes Vault/DC Circuits/Ohm's Law|Ohm's Law]] | [[Notes Vault/Physics Notes Vault/DC Circuits/Power|Power]]