p4 Flashcards
Describe how a power station works
Fuels are burnt to release steam. Steam turns a turbine. Generator makes electricity. Transformer sets correct voltage.
Define electrical current
Flow of charge from positive to negative terminal of a battery.
Describe what an electrical current is made up of
Moving electrons.
Give the unit for current
Amps (A).
Describe how we measure current
With an ammeter
Define potential difference
Work done between two points in a circuit.
Give the unit for potential difference
Volts (V).
Describe how we measure potential difference
With a voltmeter
Define resistance
Materials that oppose the flow of current.
Give the unit for resistance
Ohms (Ω).
List factors that affect resistance
Length and thickness of wires. Number of components. Temperature and type (series/parallel) of circuit. Materials.
Describe what happens to the resistance as a wire gets longer
Resistance increases.
Define a series circuit
All components connected in the same loop. Current has one path to flow in.
Give the current/potential difference/resistance characteristics of a series circuit
Current = same everywhere. Potential difference = shared between components. Total resistance = sum of resistances added.
Define a parallel circuit
Components can be set up in different loops. The current has more than one path to flow in.
Give the current/potential difference/resistance characteristics of a parallel circuit
Total current = sum of currents through each branch. Potential difference = same across each branch. Resistance = decreases as you add more resistors in parallel.
Describe how to calculate potential difference (V)
Potential difference = current x resistance. V = IR
Give the equation that links power
current and potential difference
Give the equation that links power
current and resistance
Give the equation that links energy transferred
charge flow and potential difference
