Electricity in the real world Flashcards
Energy transfer in blenders and fan
Electrical energy ——> kinetic energy of electric motors
Energy transfer in iron and kettle
Electrical energy ——> thermal energy
Energy transfer in washing machine
Electrical energy ——> kinetic energy of electric motors + thermal energy
Power
Rate at which energy is transferred per second
What appliances have highest power
Appliances that transfer electrical energy to thermal energy
Power of a component using current and resistance
Voltage x current
Power of a component using current and resistance
Current^2 x resistance
DC
Current flows in one direction
AC
Current keeps changing direction
Why use AC in the mains power supply?
Easy to use a transformer to increase/decrease the potential difference
Mains electricity frequency
50Hz
Mains electricity potential difference
230 volts
How can you see the pattern of current in mains?
Using an oscilloscope
Time interval on mains
Time taken for current to change direction then change back again
Mains supply
How we get electrical energy in uk
What are wires in the mains made of?
Copper = conducts electricity
Plastic = insulation
Brown wire
Live wire
Carries potential difference (230v)
Blue wire
Neutral wire
Completes circuit
0V
Green/yellow wire
Earth wire
Earth wire function
If something goes wrong In the circuit, the energy is transferred to earth in the wire
Fuse function
If it goes wrong, melts to shut off the current
National grid
System of transformers and high voltage cables to transfer electricity from stations to homes
What is the problem with the National grid?
Energy lost in cables
How do we solve the problem in the National grid?
Build power stations nearer to homes
Use transformers
How do transformers work?
Step up = increases voltage so less energy lost in power cables
Step down = decreases voltage so safe for home
