P5 Electricity In The Home Flashcards
What is a direct current (dc)
When the current passes through in one direction
What is alternating current (ac)
The current flows one way then the opposite way in successive cycles
What are step-up transformers
Used at power stations to transfer electricity to the national grid. These transformers are used to make the size of the alternating potential difference much bigger.
What are step down transformers
Used to supply electricity from the national grid to consumers. It decreases the size of the alternating potential difference so it is usable.
What is a mains circuit
Has a live wire, which is alternately positive and negative every cycle, and a neutral wire at zero volts.
What are sockets and plug cases made of and why
Stiff plastic materials that enclose the electrical connections. Plastic is used because it is a good electrical insulator.
What is the mains cable made up of
Two or three insulated cooper wires surrounded by an outer layer of flexible plastic material.
Colours and mames of wires in a three pin plug
The live wire-brown
The neutral wire-blue
The earth wire-striped green and yellow
All made from rubber
What is the earth wire connected to and why
Connected to the longest pin in a plug and is used to earth the metal case of a mains appliance.
What are the pins made of and why
Brass as it is a good conductor and doesn’t rust or oxidise.
What is used for the wires and why
Copper as it is a good electrical conductor and it blends easily.
What is the power supplied to a device
The energy transferred to it each second.
What happens when charge flows through a resistor
The energy is transferred to the resistor so the resistor becomes hotter
What happens when charge flows around a circuit for a given time
The energy supplied by the battery is equal to the energy transferred to every component in the circuit.
What is efficiency
The amount of energy that is usefully transferred.
