P5 Flashcards
What are mains
Mains electricity is an AC supply
What is the frequency and voltage of the UK domestic electicity supply
Frequency of 50Hz and 230v
What current is AC
alternating current coming from the mains. Current continuously varies, from positive to negative
What current is DCM
Direct current coming from mains. Movement of charge in one direction only
How many wires are there in a plug
3
Characteristics of the live wire
Brown, 230 V
Carries the alternating potential difference from the dangerous
May be dangerous if main circuit is off, as current may still be flowing through it
Characteristics of the neutral wire
Blue, 0v
Completes the circuit
Characteristics of the Earth wire
Green and yellow stripes 0v. Only carries current if there is a fault
Safety wire to stop the applience from becoming live
It is connected to the earth and to the casing
What is power
Energy transfered per second
What is power directly proportional to
Current and voltage
What is power lost proportional to
Resistance and the square of the current
Power unit
Watts W
Potential difference unit
Volts V
Current unit
Amperes A
Resistance unit
Ohms o
