Resistivity and Conductivity

?
If temperature is constant, this means that the conductor is ohmic, so resistance...
Is constant.
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Why does resistance change as the current increases in non-ohmic conductors?
Temperature rises, so Joule heating occurs where energy is dissipated, causing resistance to rise as wire heats.
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What is the correct power equation?
P=I^2R
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What happens when a filament lamp becomes white hot?
It no longer obeys Ohms Law due to temperature increasing resistance.
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Why is Joule heating difficult for precise resistances?
The resistance increases faster with increasing temperature and current.
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What do alloys contain, where the change in resistance is very small?
Constantan.
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What are platinum alloys used for due to their range of resistances being known?
Temperature sensors.
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What makes up a variable resistor?
A battery and rheostat
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What sorts of properties are resistance and conductance? (HINT: they are determined by length and cross-sectional area)
Extensive
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When length is doubled, what else is doubled?
Resistance
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When cross-sectional area is doubled, what else is doubled?
Conductance
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What is the formula for resistance?
R=pho*L/A
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What is the formula for conductance?
G= sigma*A/L
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What are correct units for resistivity and conductivity?
Sm^-1, and ohm m
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Other cards in this set

Card 2

Front

Why does resistance change as the current increases in non-ohmic conductors?

Back

Temperature rises, so Joule heating occurs where energy is dissipated, causing resistance to rise as wire heats.

Card 3

Front

What is the correct power equation?

Back

Preview of the front of card 3

Card 4

Front

What happens when a filament lamp becomes white hot?

Back

Preview of the front of card 4

Card 5

Front

Why is Joule heating difficult for precise resistances?

Back

Preview of the front of card 5
View more cards

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