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5 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Kirchoff's rules |
Rule 1 - at any junction in a circuit, the total current entering a junction is equal to the total current leaving the junction Rule 2 - for a complete loop in a circuit, the sum of emfs around the loop is equal to the potential drops around the loop |
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What is a superconductor |
- Wire or device made up of Material that has zero resistivity at and below critical temperature - when current passes through the material, there is no pd across it because its resistance is zero - current has no heating effect - Superconductor loses conductivity if its temp is above critical temp -> high temp superconductor - Uses: MRI scanners, particle accelerators, power cables |
At and below |
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Filament lamp and resistor graph |
- Filament lamp - curve with decreasing gradient because its resistance increases as it becomes hotter - Thermistor - higher the temp, greater gradient -> lower resistance |
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Positive and negative temp coefficient |
Positive - resistance of metal increases with increase of temp. Positive ions in conductor vibrate more when temp is increased. Charge carriers can't pass through metal as easily when pd is applied. Negative - resistance of intrinsic semiconductor decreases with increase of temp. Number of charge carriers increases when temp increases. Thermistor is made from this ( used as temperature sensitive component) |
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What is ohms law? |
pd across metallic conductor is directly proportional to the current through it, provided physical conditions don't change |
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