# P1 Revision

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• Created by: LBC0502
• Created on: 14-06-14 12:00
• P1 Revision
• Experiment: Leslie Cube had four different surfaces (matt dark, shiny dark, matt light and shiny light). Results: (degrees Celsius) black matt, 94.91, black shiny 98.81, white matt, 89.8, white shiny, 45.11.
• IV: Surfaces of cube. DV: Temperature of surrounding air. CV: Same starting temperature of water, the same amount of water used, the same person measuring with an infrared thermometer at the same distance from the Leslie Cube. Experiment can be repeatable by using the same method.
• Black matt is the best absorber and the best emitter of thermal radiation. White and silver surfaces are poor absorbers of thermal energy, therefore they are also poor emitters of thermal energy. However white and silver surfaces are good reflectors of thermal energy.
• Matt black radiates the most thermal energy because the surface absorbs and emits thermal energy. Silver radiates the least thermal energy and white and silver surfaces are poor emitters/poor absorbers of thermal energy but good reflectors of thermal energy.
• Kinetic Theory
• Kinetic Theory: All states of matter are made of particles, atoms or molecules. These particles are in a constant state of motion. Solids vibrate, liquids move but must be contact with another particle and gases are free to move.
• Solids: The particles are very close together and vibrate around a fixed position. Solids have a fixed shape and volume with low particle energy and the particles have a regular arrangement in rows and columns.
• Liquids: The particles are close but are free to move while being in contact with another particle. Liquids have a fixed volume and take the shape of their container. Liquids have medium particle energy.
• Gases: The particles are far apart and move randomly and quickly. Gases fill the space available and spread out. Gases have high particle energy.
• Kinetic Theory can be used to explain conduction, convection, evaporation and condensation.
• Heat and Temperature
• Heat is a form of energy. Heat is thermal energy. (Energy is measured in Joules, J/Kilo Joules, kJ)
• Temperature tells us how hot or cold an object is. Temperature is measured in degrees Celsius
• Thermal Energy Transfer Experiment: Hot water in boiling tube put into a beaker of cold water. The water in the boiling tube will decrease and the temperature of the water in the beaker will increase. The energy transfer will carry on until the temperatures are equal (equilibrium)
• If the temperature outside is 1 degree Celsius, there is a constant thermal transfer and we start to feel cold. If the temperature outside is 40 degrees Celsius, the body begins to sweat because the body produces too much heat and the sweat evaporates and cools our bodies down.
• Thermal energy is transferred from warm regions to cool regions.
• Conduction
• Experiment (Which metal is the best conductor?): pour hot water into a beaker and place the four metals (with crystals) in the hot water. IV: Metals. DV: How many crystals are heated. CV: Length of metal, time for crystals to conduct thermal energy, size of metal. Results: (in order fast-slow) Copper, Aluminium, Brass, Steel. Copper is the best conductor because the crystals in the copper were heated up quickly and the atoms in copper are arranged in a solid state.
• Metals are good conductors of thermal energy. Plastic, wood and polystyrene are poor conductors of thermal energy but are good insulators of thermal energy (stop thermal transfer). This is because the particles in an insulator are not arranged in a regular pattern (in rows and columns) and there are no free electrons.
• How do particles explain conduction (Kinetic Theory): As the metal is heated, electrons become free and the metal becomes a lattice (3D arrangement) of metal ions. These ions vibrate more and pass the kinetic energy through the metal. The more free electrons, the better the conductor. Free electrons travel through the lattice, colliding with the lattice ions and transfer kinetic and thermal energy.