physi

• How is heat transferred in solids?

  by conduction
• How is heat transferred through liquids?

  by convection
• How is heat transferred through empty space?

  by radiation
• How does Conduction work?

  1) Energy is transferred to the Kinetic energy store of the particles

  
  

  2) This thermal energy transferred causes the particles to Vibrate FASTER more OFTEN and with MORE ENERGY.

  
  

  3) The collisions transfer kinetic energy other particles will collide with the others and so the thermal energy is transferred along the solid
• What is thermal conductivity?

  The ability of an object to transfer heat. Metals have high T.C plastics have a LOW T.C so are used as insulators
• Explain Convection


  1) The heated particles (which have gained kinetic energy) will move away from the warmer region to a cooler region

  2) The fluid in the WARMER region expands and becomes less dense (Will rise above colder particles)

  
• What is a fluid?


  A substance that flows freely, such as a liquid or a gas
• What are the energy stores?

  Thermal

  Kinetic

  Gravitational potential

  Elastic potential

  Chemical

  Magnetic

  Electrostatic

  Nuclear
• What are the ways energy can be transferred?

  Mechanically, electrically, by heating, by radiation
• How is energy transferred when something is burned?

  Chemical energy transferred by heating to the thermal energy store
• How is energy transferred when a car brakes?

  Moving car has kinetic energy, brakes mechanically do work so kinetic energy decreases and thermal increases
• What is internal energy store?

  The total kinetic and potential energy of the particles in an object
• If you heat a solid what happens to the internal energy?

  The internal energy increases
• If you cool down a liquid what happens to the internal energy?

  The internal energy decreases
• Solids turning directly in to a gas is called

  sublimation
• Changes of state are _______ changes so....

  physical changes not chemical

  so if we reverse the change the material recovers its original properties
• Wat is specific heat capacity?

  The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree Celsius
• Specific heat capacity equipment

  Power supply

  Heater

  Thermometer

  Block of material

  insulation

  Ammeter

  
• How do you reduce friction?

  - For objects being rubbed together lubricants can be used to reduce friction

  - Vehicles made streamlined to reduce air resistance
• How would you reduce thermal energy loss in a building?

  • Thick walls with material with low thermal conductivity
  • Cavity walls with air gap which reduces conduction , air could cause convection current so -> filled with insulating foam
  • Double - glazed windows-> air gap reduces conduction
  • Draught excluders- around doors + windows reduces energy transfers by convection
• Why does cavity wall insulation contain pockets of trapped air?

  Air is a good insulator
• What are fossil fuels + What are the three you need to know?

  A fossil fuel is formed naturally in the earth's crust from the remains of dead plants and animals, release energy when burnt

  - Coal , Oil and natural gas
• Pros and cons of Fossil fuels

  Pros:

  - Relatively Cheap in some places easy to extract,

  - High energy output- Can be used in any conditions

  -Much of our infrastructure is designed to run using fossil fuels

  Cons:

  - Finite resource

  -Produces CO2 and increase global warming,

  -Sometimes produce toxic gases e.g. CO or Sulfur dioxide
• What is Nuclear energy and what are the pros and Cons?

  Nuclear energy is energy obtained from nuclear reactions, such as nuclear fission reactions in nuclear power stations.

  Pros:

  • Don't produce pollutants
  • Can be used in any conditions
  • Limited but UNLIKLEY to run out

  Cons:

  • Finite resource
  • Produce radioactive waste which remains harmful for thousands of years
  • Expensive
  • Chance of nuclear meltdown
  • nuclear power plants take many years to build
• What is solar power? + Pros and cons

  Power obtained by harnessing the energy of the sun's rays -> in watches and calculators

  Pros:

  • Low running costs
  • No pollutants -> no damage to environment

  Cons:

  • High upfront cost
  • Making them produces pollutants
  • Dependant on weather
  • Take up loads of space
  • No way to increase demand
• What is geothermal energy? + Pros and cons

  Thermal energy generated and stored in the earth's crust

  
  

  Pros:

  • Cheaper when used for heating
  • No pollutants
  • Renewable
  • Installing only slightly damages environment

  Con:

  • Only use it in certain region e.g., volcanic regions
  • Power plants expensive to build
• What are biofuels?

  Fuels produced from plants, algae or animal waste

  Pros:

  - Renewable + take short time to grow

  - Cheap

  - Easy to transport

  Cons:

  -Need land to grown plants -> deforestation

  -Harvesting, processing and transport of plant require energy
• What is meant when biofuel is called Carbon neutral

  They absorb the same amount of carbon dioxide while growing, as they release when they're burned
• What is hydroelectric power? Pros + Cons

  Artificial reservoir which drives electrical generators which are built inside dams

  Pros:

  - No pollution + Large amount of energy

  - Reliable source

  - Running cost are low

  - Immediate response to increase demand

  - work on large and small scales

  Cons:

  - have impact on environment

  - Often flood huge areas

  - Set up is expensive

  - Stops boats and fish from travelling
• What are tidal barrages? Pros + Cons

  Tidal barrages are big dams built across river estuaries, with turbines in them

  Pros:

  - No pollution + Large amount of energy

  - Reliable source

  - Running cost are low

  - work on large and small scales

  Cons:

  - have impact on environment

  - Often flood huge areas

  - Set up is expensive

  - Stop boats and fish from travelling
• What is wave power? Pros + Cons

  Waves turn a floating generator to generate electricity.

  
  

  Pros:

  - It is a renewable energy resource and there are no fuel costs

  - No harmful polluting gases are produced

  
  

  Cons:

  - It is difficult to scale up the designs for wave machines to produce large amounts of electricity

  - Having many wave machines can negatively affect wildlife
• In the required I-V required practical what are the three components used

  - Diode

  - Filament lamp

  - Fixed resistor

  
• What is the graph of a filament lamp?

  
• What is the graph for a diode?

  
• What is the graph for a resistor?

  
• What is an LDR?

  Light Dependent Resistor - a resistant dependent on the intensity of light

  In bright light, the resistance decreases so MORE current flow

  In darkness, the resistance is highest so LESS current flow

  
• What is a thermistor?

  A temperature dependent resistor

  In hot conditions, the resistance decreases

  In cold conditions, the resistance increases

  
• What is the Voltage, Current, Resistance like in a SERIES circuit?

  
  

  > Voltage is shared across all components V total = V1 + V2 +V3

  
  

  > Current is the same everywhere

  
  

  > Resistance is sum of Individual resistances of each component R total = R1 + R2
• What is the Voltage, Current, Resistance like in a PARALLEL circuit?

  
  

  > Voltage is the same

  
  

  > Current is shared the loops with a greater resistance will take a LOWER share of current I total = I1+I2+13

  
  

  > Resistance the more components the LOWER the total resistance
• How is the electrical power transmitted in the national gird?

  The electric power is transmitted via the national grid at lowcurrentwhich minimises power loss.