Energy
Makes things happen when transferred in a circuit
Charge
A property of some particles that stores energy in an electrostatic store
Which can then be transferred
Resistance
How difficult it is to generate a c
Direct potential difference
When potential difference is constant
Source of electricity that supplies direct PD
batteries
Situations that direct PD is useful for
To keep voltage low e.g. laptop chargers
Alternating PD
when PD reverses polarity
How alternating PD is generated
Electromagnetic induction
What are the individual wires made from and why is this good?
Copper - good conductivity
What is the plug casing made from and why is this good?
Rubber - good insulator and prevents electric shocks
What are the pins made from and why is this good?
Brass - hard
Fuse
A wire that melts if current surges through it - so it prevents fires
Static electricity
Build up of electric charge on the surface of an object
Electric field
The area around a charged object, where another charged object would experience a force
Transformer
Changes the value of PD
Step up transformer
Increases voltage
Decreases current
Reduces heat loss
—> Step up transformers use less energy so they’re more efficient
Step down transformer
Reduces voltage for safety
Purpose of National Grid
To link power stations to consumers
so they have access to a source of electricity
What 2 factors does current depend on?
PD
Resistance
Ohmic conductor
Conductor where PD and current are directly proportional
Resistance remains constant as current changes
Temperature remains constant
4 components where resistance is not constant as current changes
LDR
Thermistor
Filament Lamp
Diode
Why does PD need to be decreased between transmission lines and houses?
Lower PD - safer
Appliances are designed for 230V
Why do transmission lines transfer electricity at high potentials?
Results in low current
Less energy wasted as heat
More efficient
3 things that determine the power of a circuit
PD
Current
Amount of energy transferred
