To not affect the current flowing through the ammeter
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What is potential difference?
Electric energy per unit charge converted into other forms of energy
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Why do voltmeters have high resistance?
To make as much of the current as possible pass through the actual circuit
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What is electromotive force?
Energy per unit charge converted into electrical energy
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What is Ohm's Law?
Current is proportional to potential difference for metals at a constant temperature
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What is resistivity?
Property of a material which quantifies its resistance, defined by R = ρL/A
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What is a negative temperature coefficient?
Resistance falls when temperature rises, as more charge carriers are released as there is more internal energy. This increases current and therefore decreases resistance.
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Total resistance in series
= R1 + R2 + R3
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Total resistance in parallel
= 1/R1 + 1/ R2 + 1/R3
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What is a potential divider?
Using multiple resistors to allow certain amount of V through one branch. V2 = V1 + (R2)/(R1+R2)
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What is a rheostat?
Variable resistor which controls current
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What is internal resistance?
Opposition to the flow of current within a cell resulting in lost volts.
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Internal resistance formula
V = ε - Ir
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Other cards in this set
Card 2
Front
Why do ammeters have low resistance?
Back
To not affect the current flowing through the ammeter
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