* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Resistor
Survey
Document related concepts
Lumped element model wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Thermal runaway wikipedia , lookup
Galvanometer wikipedia , lookup
Power electronics wikipedia , lookup
Operational amplifier wikipedia , lookup
Schmitt trigger wikipedia , lookup
Negative resistance wikipedia , lookup
Superconductivity wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Voltage regulator wikipedia , lookup
Surge protector wikipedia , lookup
Opto-isolator wikipedia , lookup
Rectiverter wikipedia , lookup
Power MOSFET wikipedia , lookup
Current source wikipedia , lookup
Current mirror wikipedia , lookup
Electrical ballast wikipedia , lookup
Transcript
Resistor Potential Drop Within a material there is a + - voltage drop associated with a field. The material can be a weak conductor. • Charges may flow • Field and equipotentials exist The material will have a current I and voltage drop V. + - V Ed Ohm’s Law Many materials have a linear relationship between current and voltage. This relationship is called Ohm’s law. Resistance The ratio of the change in DP v d voltage to the current is the resistance. • Like resistance to water flow by stones A Resistance is measured in ohms (W). • 1 W = 1 V/A R V / I V IR I V / R Non-Ohmic Some materials have non-linear relations between current and voltage. • Non-ohmic materials • Fluorescent and incandescent lamps • Diodes and transistors Resistor Material can be fashioned to have a specific resistance. The symbol for a resistor is a zigzag line. • This is a resistor Resistors can be made from very long conductors. • Wound wire in a coil • Very precise Carbon composites make good resistors. Like other electrical symbols the orientation doesn’t matter. Resistivity The resistance of a material depends on the shape. • Length • Cross-sectional area The resistivity (r) is the material-dependent part of the resistance. Resistivity also depends on temperature. L Rr A r r0 (1 + 0 DT ) next