Chapter 8.7 Electrical Resistance
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What is electrical resistance?
How much current is in a circuit depends on voltage and electrical resistance of the circuit.
What increases electrical resistance?
thin wires resist electric current more than thick wires Long wires offer more electrical resistance than shorter ones Most important is the material from which the wires were made. Temperature also affects electrical resistance
What is the electrical resistance of copper and rubber
Copper has low electrical resistance Rubber has an enormous resistance
How does temperature affect electrical resistance?
The greater the temperature, the greater the resistance
What is a superconductor?
Materials whose electrical resistance reaches zero at very low temperatures
What is electrical resistance measured in?
Ohms
What are semi-conductors?
Materials that are made with either an excess or deficiency of conducting electrons by adding impurities to them
What happens between pairs of semiconductors?
the transfer of an electron though their junction can cause emission of light, as in a light-emitting diode (LED). While the absorption of light can lead to an electric current, as in a solar cell.
How does common household wiring work?
The flowing electrons in the wire, collide with atomic nuclei in the wire and convert their kinetic energy to thermal energy in the wire.
What materials have zero electrical resistance to the flow of charge?
Superconductors
Do superconductors lose electrical current during superconductivity?
No
Do superconductors lose heat during superconductivity?
No
What are high-temperature superconductors (HTS) cables able to do?
They can carry more current at a lower voltage.