AQA A GCE Physics - Current Electricity


What is current?

-Rate of flow of charge


How can you calculate current using time?



What is ΔQ measured in?
-Coulombs (unit of charge)


Define 1 Coulomb

-Amount of charge that passes in 1 second when the current is 1 ampere


How can you measure current flowing through a circuit?



Where does an ammeter need to be attached in a circuit? Why?


-Current through ammeter is the same as current through the component


Define potential difference

-Energy converted per unit charge moved


What needs to be done to electric charge to make it flow through a conductor?

-Work must be done on it


How can you work out voltage using charge?



What is ‘W’ in order to work out potential difference?
-Energy in joules, work done to move the charge


Define a volt

-Potential difference across a component is 1 volt when you convert 1 joule of energy moving 1 coulomb of charge through the component


Finish this equation in terms of the definition of potential difference.

-1V = 1JC-1


What does current for a particular potential difference depend on?

-Resistance of component


How do you calculate resistance using voltage?



What is resistance measured in?

-Ohms (Ω)


A component has a resistance of 1 Ω if a potential difference of 1 V makes a current of *A flow through it



For what sort of conductor is resistance a constant?

-Ohmic conductor


What sorts of conductors obey Ohm’s law?

-Ohmic conductor


Name 2 factors that are directly proportional in an Ohmic conductor. What must remain constant?

-Current and potential difference



How will factors such as light level or temperature have significant effects on resistance?

-Resistivity changes


Finish this sentence: “Ohm’s law is a special case; it is only true for…

-Ohmic conductors at constant temperature


What do I/V graphs/characteristics show?

-How resistance varies


What does the gradient of an I/V graph show?

-Resistance. Shallower the gradient of a characteristic I/V graph, the greater the resistance of the component



What is the I/V characteristic for a metallic conductor?

-Straight line through zero (0)


Which I/V characteristic is a curve through zero (0)?

-I/V characteristic for a filament lamp


Why doesn’t a filament lamp have the same (straight line) characteristic of a metallic conductor?

-Gets hot. Current flowing through lamp increases its temperature


The ********** of a metal increases as the temperature increases



Where are semiconductors used?



Describe semiconductors

-Nowhere near as good at conducting as metals, due to few charge carriers. If energy is supplied to semi-conductor, more charge carriers can be released. Meaning they make excellent sensors for detecting changes in their environment


Which 3 semiconductor components do you need to know about?

-Thermistors, LDRs (Light Dependent Resistors), Diodes


What does resistance of


Mrs Jones


This is a massive and very useful resource - you may wish to split it down further.  It covers both DC and AC electricity so that might be a good way to split it.  This would be an excellent discussion resource to use with friends for a revision session.  Go through the questions and discuss. For example what do the greek symbols used look like and how are they pronounced.  Alternatively you could also use this as the basis for making your own flash cards.  Comprehensive.