Energy Flashcards
Specific heat capacity
The amount of energy needed to raise the temperature of a 1 kg substance by 1 degrees Celsius
Power
The rate of energy transfer
Work done
Another way of saying energy transferred
Conduction
The processes where vibrating particles transfer energy to neighbouring particles. This is done as they collide causing energy to be transferred between their kinetic energy stores.
Thermal conductivity is a measure of how quickly energy is transferred through a material. High thermal conductivity means faster.
Convection
Where energetic particles move away from hotter to cooler regions. This occurs in gases and liquids.
Convection current is created as a region is heated the particles move faster and the space between particles increases causing density to decrease. The warmer and less dense region rise above denser cooler regions. The current is created if the heat source is constant. This is how radiators work.
Reducing unwanted energy transfers
Lubrication to reduce frictional forces
Insulation reduces the rate of energy transfer by heating
How do houses insulate
Cavity walls - air gap in between walls reduces the energy transferred by conduction through the walls
Loft insulation can reduce convection currents being created in lofts
Double glazed windows - work the same as cavity walls
Draught excluders - around doors and windows reduce energy transfers by convection
Wind power
Turbines had a generator. The wind pushes the turbine and its rotating blades turn the generator producing electricity.
+ no pollution , minimal running costs , no permanent landscape damage , no running costs , renewable
- spoil view , very noisy , only works when windy , initial costs are high
Solar power
Solar cells generate electric currents directly from sunlight. The light is absorbed and transferred to electrons. The extra energy allows them to flow through the material as an electric current.
+ no pollution , renewable , reliable , low running costs
- only works in daytime , initial costs are high , can’t increase power output
Geothermal power
Possible in volcanic area or where hot rocks lie near to the surface. The source is the slow decay of various radioactive elements. It can be used to generate electricity.
+ free energy , reliable , little damage to environment
-not many suitable locations , cost is high compared to amount of energy produced
Hydro-electric power
Requires flooding of a valley by building a dam. Water is let through the turbines from GPE to kinetic energy which is then transferred into electricity.
+ reliable , immediate response for increased electricity demand , minimal running costs
- initial costs are high , loss of habitat , big impact on environment
Wave power
Lots of wave powered turbines - work the same as wind power
+ no pollution , renewable , minimal running costs
- ruins view , disturbs seabed , fairly unreliable , hazard to boats
