Physics

• The equation for internal energy is total kinetic energy + total potential energy.
• Potential difference is the energy transferred to or from a coulomb of charge.
• Ohms law is current is directly proportional to potential difference. Resistance is indirectly proportional to current.
• The equation for specific heat capacity is change in energy = mass x SHC x temperature change.
• Specific latent heat is the amount of energy required to change the state of 1kg of a substance with no change in temperature.
• Specific latent heat of vapourisation is the amount of energy needed to change a liquid to a gas or energy released to change a gas to a liquid.
• Specific latent heat of fusion is the energy needed to change a solid to a liquid or energy released to change a liquid to a solid.
• Specific heat capacity is the amount of energy required to raise the temperature of 1kg of a substance by 1 degree celsius.
• The law of conservation of energy is energy can be transferred usefully, stored or dissipated but cannot be created or destroyed.
• Radioactive irradiation is exposing objects to beams of radiation to...

  • Kill bacteria on food
  • Kill cancerous tumors
  • Sterilisation of surgical instruments
• Radioactive contamination is the the unwanted presence of radioactive atoms on other materials.
• An alpha particle is a helium nucleus that has 2 protons and 2 neutrons.
• Rutherfords alpha particle scattering experiment...

  • Alpha particles were shot through a thin sheet of gold leaf
  • Most particles went straight through which suggested most of the atom is empty space.
  • Some deflected through large angles as they were near the nucleus
  • Some bounced back as they directly hit the nucleus
  • They concluded the mass is concentrated in the centre of the atom and the nucleus is positively charged.
• Activity is the rate at which a source of unstable nuclei decays.
• Count rate is the total number of emissions per second that are detected by a detector, such as a Geiger-Muller tube.
• The half life of a radioactive isotope is...

  • The time it takes for the number of nuclei in the isotope in a sample to halve.
  • The time it takes for the count rate from a sample containing the isotope to fall to half its initial level.
• The speed of sound in air at 0 degrees celsius is 330 m/s
• Power is the amount of energy transferred every second by an electrical appliance.
• Displacement is the shortest distance between start and finish locations.
• The centre of mass is the point at which the mass of an object may be considered to be concentrated.
• A radioactive substance gives out radiation from the nuclei of their atoms all the time.
• Current is never used up in a circuit. In a series circuit, the current is the same all around.
• Current through a resistor is directly proportional to the potential difference. This is called an ohmic conductor. This is only the case if temperature is constant.
• The resistance of a thermistor decreases as the temperature increases.