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- PHY102 Physics II © Dr.Cem Özdoğan
- 26-4 Resistance and Resistivity
- Electrons are not “completely free to move” in a conductor.
- Electrons moving through a material undergo many collisions which hinders their motion.
- The mechanical analog is friction.
- The resistance R is then
- Resistance btw any two points of a conductor is found by applying a potential difference V btw those points and measuring the current i that results.
- The SI unit for resistance is the volt per ampere. This has a special name, the ohm (symbol Ω):
- In a circuit diagram, we represent a resistor and a resistance with the symbol .
- Devices specifically designed to have a constant value of R are called resistors