physics

• how is a beta particle formed? (where is it formed)


  when a neutron changes into a proton and an electron (formed inside a nucleus)
• define ionising power?


  when radiation collides with atoms that can cause atoms to lose and form ions
• what is radioactive decay?


  when nuclear radiation is emitted by unstable atomic nuclei so they become stable
• what is a half-life of a radioactive isotope?


  the time it takes for the number of nuclei of the isotope in a sample to halve
• formula for density?


  mass(Kg)/

  volume(m3)
• what is meant by latent heat?


  the energy transferred when a substance changes state
• specific latent heat definition?


  amount of heat energy required to change the state of 1 kg of a substance without a change in temperature.
• specific latent heat formula?


  e=m x L

  (J)=(kg) x (J/kg)
• ohm's law?


  V=IR
• what is resistance?


  everything that resists or opposes the flow of electrons (ohms)
• what is 'potential difference' voltage?


  force of driving flow of electrons (V)
• what is current?


  a measure of the flow of electrons around the circuit (i)
• what is current measured in?


  amps(A)
• electric current happens when?


  charge flows
• define potential difference?


  measure of how much energy is transferred between 2 points in a circuit
• potential difference (volts) formula?


  V=energy transferred/charge

  (j)/(c)
• main ways in which we use earth's resources


  generating electricity, heating, transport
• coal, oil, gas advantages

  reliable, cheap, enough to meet demand
• coal, oil, gas disadvantages

  non-renewable, releases CO2 (climate change), releases polluting gases (acid rain)
• what's thermal conductivity?

  how quickly energy is transmitted through it by thermal conductivity
• what is a black body?


  theoretical object that absorbs 100% of radiation
• what's meant by activity?


  rate at which a source of unstable nuclei decay
• if a motor is 30% efficient what does that mean?

  30% of the energy is usefully transferred, where 70% is dissipated
• the five energy stores are?


  gravitational potential, elastic potential, kinetic, thermal and chemical
• 3 green house gases


  methane, water vapor, carbon dioxide
• what are factors that affect rate of heat loss from building

  thickness and thermal conductivity of roof and walls,
• renewable resources


  geothermal, solar, hydroelectric, tidal, wave, wind, biofuels
• non-renewable energy sources


  coal, oil, gas, nuclear fission
• what's an isotope?


  atoms of the same element with different number of neutrons
• unit of power

  watts
• work done is


  energy transferred when a force moves an object
• what is a closed system


  where no energy can be transferred to/ from surroundings (total energy stays the same)
• 4 ways energy can be transferred


  mechanically, waves, electric current, heating
• what's a system?


  an object/ group of objects
• what do you need to measure for specific heat capacity?


  mass, temperature rise and time taken
• what activities increase greenhouse gases?


  deforestation, burning fossil fuels and livestock farming
• infrared radiation is


  a type of electromagnetic radiation
• what is a material with low thermal conductivity

  thermal insulators
• definition of specific heat capacity?

  amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius
• formula for specific heat capacity?

  change in thermal energy = mass × specific heat capacity × temperature change