93-94 - Mains Electricity and the Home Flashcards
What are the two types of currents (+ give examples)?
Alternating current - mains supply
Direct current - battery supply
What voltage is the UK mains supply?
230V
What is the definition of AC?
Current which constantly changes direction
What’s the frequency of the mains supply?
50 hertz
What is the definition of direct current?
Current flows in the same direction
What is the difference beteeen an AC supply and a DC supply’s oscilloscope readings?
AC would be a wavy line, DC would be straight
What does the vertical height of an AC trace on an oscilloscope show?
The input voltage or potential difference
How do you find the voltage on the trade of a DC supply?
Distance from straight line to centre
Name five possible electrical hazards in the home
Long cables
Frayed cables
Cables touching something hot/wet
Water near sockets
Inserting things into sockets
Damaged plugs
Too many plugs per socket
Light fixtures without bulbs
Appliances without covers
What is a wire made of?
Copper core and coloured plastic coating
What are the three wires within a cable?
Live - brown
Neutral - blue
Earth - green/yellow
What’s the potential difference for a blue wire?
0 Volts
What happens to the voltage in a live wire?
Alternates between positive and negative voltage
What is the purpose of the earth wire?
Connected to a fuse to prevent fires
What happens if a live or neutral wire touched the metal case?
The earth wire carries the electricity away to earth
