Current Voltage characteristics, Resistivity

What is electric current

The rate of flow of charge

define potential difference

the energy transferred per unit charge

What does Ohm’s law state?

in an ohmic conductor, current is directly proportional to the potential difference

(given physical conditions remain constant)

What does the IV graph of an ohmic conductor look like?

What is the IV graph for a semiconductor diode?

What is a Filament lamp?

a component that contains a length of metal wire, so it heats up as current increases.

What can be said about the behavior of a filament lamp when the current is very low?

It will obey Ohm’s law

What is the IV graph for a Filament lamp?

Define resistivity

The measure of how easily a material conducts electricity

What’s the formula for resistivity?

What can be said about the resistance of a metal conductor as the temperature increases?

Its resistance increases

What material has the opposite affect from heat?

Thermistors, their resistance decreases as their temperature increases

What is a superconductor

a material which, below its critical temperature, has zero resistivity

What are some applications for superconductors?

• power cables - reduce the energy loss through resistance

• strong magnetic fields (maglev trains, MRI scans and other medical applications)