Gravitational potential: Energy an object has because of its height above the ground.
Elastic potential: Energy an elastic object has when it is stretched or compressed.
Thermal: Energy an object has because of its temperature.
Chemical: Energy that can be transferred by chemical reactions involving foods and fuels.
Nuclear: Energy stored in the nucleus of an atom.
Efficiency = useful energy/ total energy
The frequency of the mains in the UK is 50Hz and the voltage is 230V
Earth wire: Yellow and Green and it’s a safety to stop the appliance from becoming live.
Neutral wire: Blue and it completes the circuit.
Plastic is used for plug coating as it‘s a good insulator.
Live wire: Red and it carries a potential difference of 230V
Fuse: A device that melts when the live wire touches the neutral wire.
Transformers: Devices that change the potential difference of an alternating current.
The current in a diode only flows in one direction - the forward direction.
The properties of a solid are:
High density
Fixed volume
Fixed shape (unless deformed by an external force)
Properties of a liquid:
Lower densities than solids
Fixed volume
Shape is not fixed so they can flow
Properties of a gas:
Low density
No fixed volume or shape
Can be compressed and can flow
Spread out to fill all available space
When the temperature of a substance is increased, the kinetic store of energy in its particles increases meaning the particles vibrate and move faster.
Specific latent heat: The amount of energy needed to change the state of 1kg of a substance without changing its temperature
Specific heat capacity: The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree.
Plum pudding model: A cloud of positive charge with electrons embedded in it.
Rutherford experiment: Shot alpha particles at gold foil and 1/8000 bounced back which showed atoms have a dense, positive nucleus.
Neils Bohr calculated that electrons orbit atoms at fixed distances and these orbits are called shells.
The radius of an atom is 1 X 10^-10m
Ionisation: The process of an atom gaining or losing electrons.
Alpha particles have two protons and two neutrons. They have the highest ionising power and only travel a few cm in air.
Beta particles have high ionising power and travels around 1m in the air.
Gamma radiation has the lowest ionising power, has virtually unlimited range in air and can only by stopped by a few centimetres of lead or metres of concrete.
Half- life: The time taken for the number of nuclei to halve.
Ionisingradiation: radiation that can knock electrons off atoms, causing them to become positively charged ions
Nuclear fission: when a heavy nucleus splits into smaller fragments releasing energy
Radioactive decay: the spontaneous emission of alpha, beta or gamma radiation from the nucleus of an unstable isotope