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LC electricity resistance, semi conductors and other stuff!
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What is an emf?
When a voltage is applied to a circuit
What are the sources of an emf (electromotive force)
electrical mains
thermocouple
A cell
What is ohm's law?
the voltage is proportional to the current
for a metallic conductor at a constant temperature, the current will be proportional to the voltage
Draw the graph for current and voltage in metals.
and how is current carried?
graph directly proportional
by
electrons
Draw the graph for current and voltage in filament bulbs.
and how is current carried
by electrons
curved surface because at higher voltages the increased heat increases resistance, and limits the current
Draw the graph for current and voltage in gases.
and how is current carried
By ions
at higher voltages, no more ions can be created, limiting the current
higher curve slant than f.b
Draw the graph for current and voltage in vaccum.
and how is current carried
The cathode must be warmed.
At higher voltages, electrons move across the vacuum
graph: behind middle up curve slant to the right
Draw the graph for current and voltage in electrolysis (inactive electrodes).
and how is current carried
by ions
graph: directly proportional behind the middle
Draw the graph for current and voltage in electrolysis (active electrodes).
and how is current carried
by ions
directly proportional
What is resistance?
of an object within an electrical circuit is defined as the ratio of the voltage across it to the voltage flowing through it
R=V/I
measured in ohm's
What varies resistance
the length (l)
the cross-sectional area (A)
the material from which the object is made (p)
What is resistivity
R=pl/A
the resistance of a unit of that material
What is the Wheatstone bridge used for?
Author
cat126
ID
351186
Card Set
LC electricity resistance, semi conductors and other stuff!
Description
revision questions
Updated
2020-03-14T13:17:05Z
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