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Flashcards in Safe Electricals Deck (14):

Describe and recognise how resistors can be used to change the current in a circuit

A variable resistor (rehostat) has a resistance that can be altered. A current that flows can be changed by simply moving the sliding contact if the variable resistor from one end to another


Describe how variable resistors can be used to change the current in a circuit

- longer wires give less current
- thinner wires give less current


What is resistance measure in



Recall the colour coding for live, neutral and earth wires

Live - brown
Neutral - blue
Earth - green/yellow


State that an earthed conductor cannot become live

This is because earthing means connecting the conductor to earth, which takes away any charge that could electrocute people


Describe reasons for the use of fuses and circuit breakers

They are safety features; prevent fires, injury and death in the home by breaking the circuit of an appliance if a fault occurs

A circuit breaker can be reset. A fuse has to be replaced.


Recognise that double insulated appliances don't need earthing

The appliance is a non conductor and cannot become live


Explain how variable resistors can be used to change the current in a circuit

Longer wires have more resistance
Thinner wires have more resistance


Describe the relationships between current, voltage and resistance:

- for a given resistor, current increases as voltage increases and vice versa
- for a fixed voltage, current decrease as resistance increases and vice versa


Equation for resistance

Resistance = voltage / current


Describe the functions of the live, neutral and earth wires

Live - carries the high voltage
Neutral - completes the circuit
Earth - a safety wire to stop the appliance becoming live


Calculate power

Power = voltage X current


Explain how a wire fuse reduces the risk of fire; if the appliance develops a fault:

- too large a current causes the fuse to melt
- preventing flow of current
- prevents flex overheating and causing fire
- prevents further damage to appliance


Explain the behaviour of simple circuits in terms of the flow of electric charge

A circuit is a complete loop that allows an electric current to flow. Electrons flow around the circuit from the negative electrode of the power source to the positive electrode.