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Hint
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Answer
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measure of current that flowed within a period of time
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charge
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what is the unit for charge
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coulombs
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what is the formula linking charge, current and time
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Q=It
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what is the charge of an electron
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-1.6x10^-19 C
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how can we find the number of electrons that have flown past a point
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identify the charge
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use number of electrons=charge/charge of an electron
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does conventional current flow from positive to negative or negative to positive
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positive to negative
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how does electron flow differ to conventional current
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electron flow is negative to positive
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what is Kirchoff's first law
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total current flowing into a junction=total current flowing out of a junction
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what is meant by potential difference
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work done per unit charge
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what formula links energy, power and time
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E=Pt
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which formula links charge, energy and voltage
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V=E/Q
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how does the temperature affect the resistance of wires and resistance
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increasing temperature increases the resistance
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why does increasing the temperature of a wire increase its resistance
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the particles in the wire vibrate faster, slowing the flow of electrons, increasing the resistance
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the current through a conductor is directly proportional to the potential difference and inversely proportional to the resistance
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Ohm's law
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what does a diode do
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only allows current to flow one way in a circuit
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what factors affect the resistance of a wire at constant temperature
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length
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cross-sectional area
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resisitivity
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how does resistivity of a metal vary with temperature
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as temperature increases the resistivity of a metal increases
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what is the resistivity of a superconductor below the critical temperature
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zero
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what happens to the resistance of a wire as the length is increased
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it increases
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what happens to the resistance of a wire as the cross-sectional area is increased but all other factors are kept the same
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it decreases
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the average velocity of charge carriers moving through a material due to an electric field
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mean drift velocity
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do conductors or insulators have the highest number of charge carriers
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conductors
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do semiconductors or insulators have the highest amount of charge carriers
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semiconductors
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give an example of a material with a high number of charge carriers
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metals/graphene
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give the number of charge carriers for the perfect insulator
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zero
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a circuit that has two or more resistors in series with a power supply
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potential divider
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a potential divider has two resistors in series. If the output voltage is half the supply voltage, the resistors must be
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identical
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what are some uses of a variable divider
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volume control for a loud speaker
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brightness control for a dimmer switch
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variable power supply
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what is the energy supplied by a power supply per coulomb of charge
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electromotive force
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what is a power supplies internal resistance
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the resistance of the power supply itself
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the voltage measured across the terminals of a source
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terminal potential
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what is meant by the difference between the electromotive force of a power supply and the terminal potential
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lost volts
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what happens to the resistance of an LDR when placed in bright light
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it decreases
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how can the resistance of a thermistor be increased
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cool the thermistor
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