Physics

• Energy can be transferred, stored or dissipated but it can't be created or stored
• Radioactive decay is where a nucleus gives out radiation to become stable
• An insulator is material that doesn't allow the easy flow of energy
• Efficiency is how good a device is at transferring energy input to useful energy output
• When the current in a circuit is increased, the resistance decreases
• In a series circuit potential difference is shared, current is the same everywhere and the resistance adds up
• A conductor is material that allows internal energy to be transmitted through it easily
• Red Shift is the observed change in wavelength of light from a distant star moving away from Earth
• Elastic deformation is a temporary deformation of a materials shape that is self-reversing once the force or load is removed
• There are 7 energy stores: chemical, gravitational, kinetic, thermal, elastic, nuclear and magnetic
• Isotopes are atoms of the same element with different numbers of neutrons
• Inertia is the tendency of an object to continue in its state of rest or constant motion unless acted upon by an external force
• There is more red-shift when a galaxy is further away as it will be moving the quickest away from Earth
• Dissipation is ways in which energy is wasted
• There are 4 energy transfers: mechanical, electrical, heating, radiation
• Contamination is where a radioactive isotope gets onto a material where it should not be
• Irridation is the process of exposing a material to alpha, beta or gamma radiation
• Irridation kills living cells
• Electric shocks happen because the body has a potential difference of zero and when you touch a live wire a large p.d. is produced across your body allowing current to flow through your body
• JJ Thompson discovered electrons. He proposed the plum pudding model where spheres of positive charge had negative electrons embedded in it
• John Dalton propsed the idea that solid matter was made up of tiny spheres
• Rutherford conducted the alpha scattering experiment. Most particles went through, some deflected and some deflected back the way they came. He said the atom is concentrated in a nucleus thus having a positive charge
• In a parallel circuit, potential difference is the same, current is shared and resistance decreases as more loops are added
• When materials are rubbed together, negatively charged electrons are scraped off one and dumped on the other. This leaves materials electrically charged causing a build up of static
• The live wire has a charge of 230 volts and has a frequency of 50 hertz
• Alpha radiation is the emitting of a alpha particle(2 neutrons and 2 protons) from the nucleus
• Beta radiation is a fast moving electron released from the nucleus. During this process, a neutron is turned into a proton
• Gamma radiation is waves of electromagnetic radiation released by the nucleus
• Fusion is the joining of small nuclei
• Fission is the splitting of a large unstable nucleus
• Half-life is the time taken for the number of radiactive nuclei in an isotope to halve
• A closed system is a system where no energy can enter or leave