AQA A GCE Physics - Current Electricity

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What is current?

-Rate of flow of charge

 

How can you calculate current using time?

-ΔQ/Δt

 

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?

-Ammeter

 

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

-Series

-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?

-W/Q

 

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?

-V/I

 

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

-1A

 

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

-Temperature

 

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

-Resistance

 

Where are semiconductors used?

-Sensors

 

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

Comments

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.

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