# Electricity

• Created by: ajshala1
• Created on: 22-09-18 12:18
Define Current
Current is the rate of flow of charge
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Define Potential Difference
Potential difference is the work done per unit charge
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Define Resistance
Resistance is defined as voltage/current
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State Ohm's Law
Ohm's law is a case where current is directly proportional to voltage
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Give the formula for Resistivity
Resistivity=(Resistance X Area) / Length
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Give the formula for Resistance in terms of Resistivity
Resistance=(Resistivity X Length) / Area
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Describe the effect of temperature on the resistance of metal conductors
Increasing the temperature, increases the amount of kinetic energy within the metal. This means electrons have to flow through a more turbulent mass of atoms, causing more collisions. Increasing the resistance.
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Describe the effect of temperature on the resistance of thermistors.
Increasing the temperature means more electrons can break free of their atoms to become conduction electrons, which carry charge. This means there is more current flowing, decreasing the resistance.
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Name an application of thermistors
Thermistors can be used as thermostats to monitor and control the temperature in rooms, fridges and incubators.
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Define superconductivity
A property of certain materials which have zero resistivity at a critical temperature
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Name an application of superconductors
Superconductors are used when strong electromagnets are required or to reduce energy loss in transmission of electric power.
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How do you calculate resistance in a series circuit?
Rt = R1+R2
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How do you calculate resistance in a parallel circuit?
1/Rt = 1/R1+1/R2
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How do you calculate current in a parallel circuit?
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How do you calculate current in a series circuit?
Same
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How do you calculate voltage in a parallel circuit?
Same
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How do you calculate voltage in a series circuit?
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Give the formula which links Energy and Current
E=IVt
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Give the formula which links Power and Current
P=IV
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Give the formula which links Power and Current^2
P=I^2 R
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Give the formula which links Power and Voltage^2
P=V^2/R
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State Kirchoff's First Law
the total charge flowing into a junction of wires must equal the total charge flowing out of the junction
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State Kirchoff's Second Law
the sum of the Emf’s in any closed loop in a circuit must be equal to the sum of the potential differences in the closed loop of a circuit
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State the formula which links emf and charge
EMF = E/Q
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State the formula which links emf and current
EMF = I(R+r)
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Define electromotive force
Electromotive force is the energy provided by a cell per coulomb of charge passing through.
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## Other cards in this set

### Card 2

#### Front

Define Potential Difference

#### Back

Potential difference is the work done per unit charge

### Card 3

#### Front

Define Resistance

#### Back ### Card 4

State Ohm's Law

#### Back ### Card 5

#### Front

Give the formula for Resistivity

#### Back 