energy stores ✩

• Latent heat can be measured from a heating or cooling curve line graph, where horizontal lines represent energy used to change the state of a material
• Energy is transmitted by conduction, convection, or radiation
• Temperature is a measure of the average kinetic energy of the molecules
• Lead warms up and cools down fastest due to its low specific heat capacity
• Bricks take longer to heat up and cool down, making them useful in storage heaters
• Most heaters are filled with oil (1,800 J/kg°C) or water (4,200 J/kg°C) as they emit a lot of energy as they cool down and stay warm for a long time
• Internal energy is the total energy stored by the particles making up a substance or system, consisting of potential energy stores (like gravitational and elastic potential) and kinetic energy stores
• Kinetic energy is the movement energy of particles and is crucial when heating a substance, as it increases the internal energy
• Temperature is a measure of the average internal energy of a substance, with higher internal energy leading to higher temperatures
• The equation for change in internal energy is: change in internal energy = mass × specific heat capacity × change in temperature
• In the example given, with 800 grams of water at 20 degrees celsius and 20 kilojoules of energy transferred, the final temperature would be 25.95 degrees celsius (or rounded to 26.0 degrees celsius)
• Specific latent heat is the energy required to change one kilo of a particular substance from one state to another without changing its temperature
• Specific latent heat depends on two things: the type of substance and the amount of that substance
• There are two types of specific latent heat:

  • Specific latent heat of vaporization: energy change when a substance changes between a liquid and a gas (evaporates or condenses)
  • Specific latent heat of fusion: energy change when a substance changes between a solid and a liquid (melts or freezes)
• The equation for specific latent heat is: energy = mass of the substance × specific latent heat
• During state changes, the temperature remains constant as the energy provided is used to weaken or break the forces holding the particles together, not to increase internal energy
• In a cooling process, the specific latent heat values refer to the amounts of energy released at each stage, not required
• Double glazed windows have lower thermal conductivity compared to single glazed windows, reducing the amount of thermal energy passing through and leaving the house interior
• Constructing buildings with materials of low thermal conductivity and thick walls can reduce thermal energy transfer from a house
• Specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius
• To determine the specific heat capacity of a material, a practical experiment is conducted using vegetable oil
• Steps in the practical experiment to determine specific heat capacity of vegetable oil:

  • Place a beaker on a balance and set it to zero
  • Add oil to the beaker and record its mass
  • Place a thermometer on an immersion heater in the oil and note the starting temperature
  • Insulate the beaker to prevent thermal energy loss
  • Connect a joulemeter to the immersion heater to measure energy input
  • Leave the setup for around thirty minutes for the temperature to rise
  • Read the total energy input and final temperature of the oil
  • Calculate specific heat capacity using the equation: change in thermal energy divided by mass multiplied by temperature change
• Possible sources of inaccuracies in the experiment:

  • Thermal energy passing on to the beaker and into the air can be reduced by using an insulator with lower thermal conductivity
  • Ensure the immersion heater is fully submerged to prevent energy loss
  • Incorrectly reading the thermometer can be avoided by using an electronic temperature probe
  • Stirring the oil can help spread thermal energy more evenly
• Specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius
• To calculate the change in thermal energy in joules, use the equation: mass (in kilograms) * specific heat capacity * temperature change (in degrees Celsius)
• Specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change in temperature
• Specific latent heat of fusion is the energy required to change 1 kilogram of a substance from a solid to a liquid with no change in temperature
• Energy for a change of state in joules = mass in kilograms × specific latent heat
• Cavity wall insulation

  • Reduces energy transfer through outer walls by trapping air in pockets between inner and outer walls
• Loft insulation


  • Cost-effective way using fiberglass material with trapped air between fibers to reduce energy transfer by conduction
• Reducing energy transfer

  Using insulation techniques
• Heating buildings

  Entails using a variety of methods such as gas central heating systems, solid wood fires, and electric heating systems
• Heating homes can be expensive
• Radiator reflectors

  • Reflect radiation away from the wall and back into the room to reduce energy transfer by radiation
• Double glazing


  • Consists of two panes of glass with dry air or vacuum between them to slow energy transfer by conduction and prevent energy transfer by convection
• Wall thickness

  • Affects the rate of transfer by conduction, thicker walls with lower thermal conductivity reduce energy transfer
• Solar panels


  • Absorb infrared radiation from the Sun, can be used for generating electricity or heating water, fitted on south-facing roofs to maximize infrared absorption
• Energy

  Never created or destroyed, only transferred between different forms and objects
• Forms of energy

  • Thermal or internal energy
  • Kinetic energy
  • Gravitational potential energy
  • Elastic potential energy
  • Chemical energy
  • Magnetic energy
  • Electrostatic energy
  • Nuclear energy
• Energy transfer


  1. Mechanical

  2. Electrical

  3. Heating

  4. Radiation (light or sound waves)