17.1 Current and Ohm's Law
Current and Ohm’s Law
| CURRENT AND OHM’S LAW | |
|---|---|
| Electric Current | I = Δq / Δt SI Unit = Amps (A); 1A = 1C/sConventional Current - Flow of positive charges (Current in a conductor is actually the flow of electrons in the opposite direction.) |
| Ohm’s Law | ΔV = IR |
| Resistance | R = ΔV / I SI Unit = Ohms (Ω) |
| Power Dissipatedby a Resistor | P = ΔVI = I2R = ΔV2 / R SI Unit = Watts (W) |
| Resistivity | R = ρ L / A ρ = Resistivity  L = Length  A=Area |
| TemperatureDependence ofResistance | ρ = ρ0 (1+ αΔT) α = temperature coefficient of resistivityR = R0 (1+ αΔT) |
| Superconductor | A material whose resistance decreases to virtually zero at low temperatures. |