Science A (Core): Physics
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What are the 3 ways in which energy can travel?
Conduction, convection and radiation
Explain what conduction is
When energy is passed from one particle to another (via vibrations)
What type of materials are good conductors and what type of materials are bad conductors (good insulators)?
Metals are good conductors (e.g. copper) and non-metals are good insulators (e.g. plastics)
Does conduction happen best in solids, liquids or gases? Explain your answer
Solids – the particles are close together
Explain what convection is
Heat rises because particles gain energy, spreading out and becoming less dense – when they lose energy they become more dense, sinking and forming the convection current
What is a vacuum and which forms of energy movement does it stop (convection / conduction / radiation)
A vacuum is a space with no particles – this prevents energy transfer via conduction and convection (radiation can pass)
Does convection happen best in solids, liquids or gases? Explain your answer
Convection happens best in liquids and gases as the particles are able to move
How does the outside temperature affect the rate at which heat is transferred?
The greater the temperature difference the greater the heat transfer (loss or gain)
What type of objects usually emits radiation energy?
Hot objects as well as black objects are good emitters of radiation
What type of material absorbs radiation and what type of material reflects radiation?
Black matt materials absorb radiation the most White shiny materials reflect radiation the most
Which home insulation methods are usually the most cost effective?
Cavity wall insulation
Give 3 examples of how energy can be lost from a house and explain how heat loss can be reduced
Windows – use double glazing / thick curtains Walls – use cavity wall insulation Loft – use loft insulation (fibre glass)
What are the 10 types of energy? Explain each one
Electrical; light; sound; kinetic (movement); nuclear; thermal (heat transfer from hot to cold objects); radiant (electromagnetic radiation from hot objects); gravitational potential; elastic potential; and chemical
What 2 things affect the amount of energy an appliance transfers?
Power and length of time the appliance is on
What is power, and what units is it measured in?
Power means “how much energy per second”, measured in watts (W) or kilowatts (kW)
What is the equation for working out power?
Power (W) = Energy (J) ÷ Time (s)
What units is energy measured with?
Joules (J) or kilojoules (kJ)
Draw out the following energy transfers: - Toaster Battery operated torch Skateboarding down a hill Solar operated fan
Toaster – electrical → thermal Battery operated torch – chemical → electrical → light (+ thermal) Skateboarding – gravitational potential → kinetic → thermal (frictional) Solar operated fan – light → electrical → kinetic
What happens to the energy that is wasted in energy transfers?
It is transferred to the surroundings (usually heating the surroundings up)
What does energy efficiency mean and how is it worked out?
Efficient devices transfer more energy (wasting less) Efficiency = useful energy output ÷ total energy inpu
How would you make these items more efficient: - Toaster Light bulb Car
Toaster – stop it losing light Light bulb – stop it losing heat Car – stop it losing heat and sound
What are the different energy resources?
Solar; tidal; wind; geothermal; hydroelectric; fossil fuels; nuclear; wave
What are the 3 types of fossil fuel?
Coal, oil and natural gas
How can you work out the cost of energy transferred from the mains supply?
Energy transfer = kilowatt hours x cost per unit