conduction, convection and radiation

• conduction happens in solids
• convection happens in fluids (gas and liquids)
• radiation happens in empty space
• conduction = vibrating particles transfer energy to neighbouring particles through kinetic energy
• in conduction particles vibrate faster leading to more successful collisions
• metals are good conductors of heat
• plastics are bad conductors of heat
• convection happens because when the spaced out particles gain heat energy they start to gain kinetic energy and they move along from the warmer to cooler areas
• the warmer particles spread out during convection and become less dense
• in a flask when heated the particles at the bottom gain heat and rise to the top of the liquid as they become less dense. the cooler particles are then at the bottom of the flask and the cycle repeats. the heated particles start to lose energy and lose heat. this cycle is called convection current.
• to reduce convection you stop the free flow of fluids. e.g. sleeping under a blanket stops all of the warm air from escaping.
• examples of convection currents are the ocean and radiators
• conduction and convection currents are both based on particles gaining kinetic energy. however in convection the particles only gain energy and in convection particles move.
• radiation is when heat energy can be transferred without particles (through a vacuum)
• in radiation energy is carried using infrared waves
• the hotter an object is the more radiation it emits