Term
What is electrical energy? 

Definition
Energy transfer due to an electric current. 


Term
Why is electricity so useful? 

Definition
It can be converted into almost any other type of energy. 


Term

Definition
The flow of electrons round a circuit 


Term
What do you need for a current to flow? 

Definition
A complete circuit Power Source (Battery)



Term

Definition
In amps, using an ammeter 


Term

Definition
Opposition to the drive of charge. 


Term

Definition
The energy used to move charges around. Like "Electrical pressure" Voltage = Current x Resistance. 


Term
How can the current in a circuit be changed? 

Definition
If you increase the voltage, the current goes up. If you increase the resistance, the current goes down.



Term
How do we measure the power of devices? What is it? 

Definition
Power (in Watts, W) = energy transferred (in Joules, J) / Time taken (In seconds, S). This power is the rate of energy transfer 1 Watt = 1 J/s 1 Kilowatt = 1000 watts. 


Term
How can we work out the energy supplied to a device? 

Definition
Energy transferred (kW h, Kilowatthours) = Power of device (kW) x Time in use (hours, h) 


Term
How can we use kW h to calculate the cost of electricity? 

Definition
Total cost = number of kW h used x cost per kW h 


Term
What is the national grid? 

Definition
A network of cables connecting power stations to homes and other buildings. 


Term
Why does the national grid need transformers? 

Definition
Transmitting electricity at a high voltage reduces power loss making it more efficient. We use stepup transformers to step this voltage up to the grid voltage. We use stepdown transformers at local substations to step the grid voltage down to 230 volts for use in homes and offices. 


Term
Why does increasing the voltage reduce wasted energy? 

Definition
To transmit a lot of electrical power you need a high voltage or a high current because Power = Current X Voltage. However, when we increase the current then the cables become very hot which is a waste of energy. Therefore it is cheaper to increase the voltage. 


Term
How do we work out electrical power? 

Definition
Power (W) = Current (Amps) x Voltage 

