Electricity is secondary source of energy- it needs wind or waves to produce it. WInd and waves are renewable because they will not run out.
Coal is burned to power generate electricity and it is non-renewable.
Using any renewbale resouce will have an economic effect as many of the renewable energy resources have a high cost to set up.
- more efficent use of current sources
- replace non-renewable resources with renewable
The national grid collects electrical energy generated in power stations and distributes it.
Electric motors, form the basis of a vast range of electrical devices both inside and outside the home.
To reverse the direction of rotation;
- reverse the direction of the current around the coil by reversing the power supply to the brushes
- reverse the magnetic field.
Real motors have several seperate coils of wire wrapped around the armature, each with its own pair of commutator segments.
Electrical energy is transferred to an appliance by electric current through a cable.
The appliance then transforms the electrical energy into other forms (eg light, sound) Some energy will always be 'lost' as heat in the cable.
When devices transfer energy, only part of it is usefully transferred to where it is wanted and in the form it is wanted.
Efficiency = ( useful output/total input ) x 100 %
The above is called the principle of conservation of energy.
Solar cells are not very efficent devices.
Insulation in houses is very importan as less energy is required to heat them.
A fuse is a short, thin piece of wire with a low melting point. When the current passing through it exceeds the fuse's current rating, the fuse wire gets hot and melts/breaks preventing damage to the cable, appliance and user.
All electrical appliances with outer metal cases must be earthed.
Most modern houses have circuit breakers. They depend on an electromagnet which seperates a pair of contacts when the current becomes high enough.
Residual Current Circuit Breakers (RCCB) - an electromagnetic device which puts a gap in a circuit by seperating two contacts if the current exceeds a safe value.