Physics assessment September 2016 Flashcards
What are kilowatt-hours?
Units of enegry
Give an example of an electrical appliance that has to transfer electrical energy in to other forms?
Sound and Heat energy in a radio
Sound, heat and kinetic in a hair dryer
What is energy measured in?
Joules (j)
What is power measured in?
Watts or killowatts
Name 8 renewable energy sources?
Wind power Solar Cells Hydroelectric Power Pumped Storage Wave Power Tidal Barrages Geothermal Energy Biofuels
Where does tend to flow away from?
From hotter objects to cooler surrondings
What 3 ways is heat transferred?
Radiation
Conduction
Convection
What is heat radiation?
The transfer of heat energy by infrared radiation
Which 2 ways involve the transfer of energy by particles?
Conduction
Convection
What is the main form of heat transfer in solids?
Conduction
What is the main form of heat transfer in liquids and gases?
Convection
Infrared radiation can be emitted by…..?
Solids
Liquids
Gases
An object can both….and…. infrared radiation
Absorb
Emit
The bigger the temperature difference between a body and its surroundings the….?
Faster energy is transferred by heating
When you heat a substance you give the particles more….
Kinetic energy
What is conduction of heat energy?
vibrating particles pass energy to others transferring heat
Why do metals conduct so well?
Free electrons
What is convection?
Energetic particles move from the hotter regions to the cooler ones and take their heat energy with them
What are convection currents?
Change in density
Steps in convection currents?
Particles spread and water/air expands
Hot water/air rises as its less dense
Fast particles collide with slow transferring heat
Cool water/air falls as its now more dense
What is reflection of light?
Is what allows us to see objects. Lights bounces of them into our eyes
What is the normal?
An imaginary line that’s perpendicular to the surface at the point of incidence.
When light is travelling in the same direction reflects from an uneven surface what will the light do?
Light will reflect off at different angles
What rules apply when drawing a ray diagram?
The image is the same size as the object.
The object and image are the same distance away from the mirror.
What 3 things is the virtual image?
Laterally inverted
Same distance
Same size
What does laterally inverted mean?
The lefts and right sides are swapped
What do waves do when they reflect?
They obey the law of reflection
What is the angle of incidence ?
Its in between the incoming ray and the normal
What is the angle of reflection?
Its in between the reflected ray and the normal
What are waves?
They are vibrations that transfer energy from one place to another
Which sound waves travel through a medium?
Sound waves and seismic waves
What do transverse waves do?
The vibrations are at right angles to the direction of travel and energy transfer
What are transverse waves?
Light, water and s waves
What do longitudinal waves do?
The vibrations are along the same direction as the direction of travel and energy transfer.
They are parallel
What are longitudinal waves?
Sound waves, p waves and waves in a stretched spring
Longitudinal waves show what?
Areas of compression and rarefraction.
Compression=spring close together
Rarefraction=spring far apart
What is the amplitude?
maximum vibration from its undisturbed position. (half the height of a wavelength,bigger it is the more energy)
What is wavelength?
The distance between a point on one wave and the same point on the next wave.
What is frequency of a wave?
It is the number of waves produced each second.
Number of waves that pass a certain point each second.
What is V in the speed equation?
Is the wave speed in metres per second
What is f in the speed equation?
Is the frequency in Hertz
What is lambda in the speed equation?
Is the wave length in meters
What is refraction?
The change in direction of sound and light waves when passing across two substances with different densities
What is diffraction?
Spreading out of waves as they pass an object or through a gap between objects
When does significant diffraction take place?
When the wavelength is of the same order of magnitude as the gap
What is redshift?
Increasing in wavelength of light as a galaxy moves away from us
Distant galaxies are moving away from us, and that the further away a galaxy is…?
The faster its moving
Microwaves are coming from every direction in space and this is called?
Cosmic microwave background radiation
CMBR waves
The bigger the redshift?
faster galaxy is moving away from us
further galaxy is moving away from us
What is reflection?
Boncing back of waves off materials they cant easily pass through
What is the ionosphere?
A charged layer in the atmosphere.
Microwaves can penetrate to communicate with satellites.
The big bang theory?
The universe started at a very initial point and exploded
Heat can be transferred by?
Conduction
Convection
Radiation
Dark matt surfaces are better at what?
Absorbing heat energy that light shiny surfaces
What does radiation involve?
Electromagnetic waves
Poor conduction of heat are called?
Insulators
Metal atoms left behind are now what?
Charged metal ions
The hotter the metal the…
more kinetic energy the vibrations have
When does convection occur?
When particles with a lot of heat energy in a liquid or gass move and take the place of particles with less heat energy
Why do liquids and gasses expand when heated?
The particles move faster when heated, they take up more volume
Liquid or gas is less dense in hot areas and compared to when to when they are in cold areas, this means?
It will rise into cold areas
The hotter an object the more …
infrared radiation it emits
What type of object radiates heat energy faster?
A thin flat object
Heat is lost through?
The roof Windows Walls Floor Gaps around the door
Ways to reduce heat loss?
Fitting carpet
Curtains
Draught excluders
The gap between two panes of glass is filled with what?
Air
Heat loss through walls can be reduced by?
Cavity wall insulation
What does cavity wall insulation reduce?
Air circulation inside the cavity.
Reducing heat loss by convection and conduction
Types of energy?
Magnetic Kinetic Heat Light Gravitational potential Chemical Sound Electrical Elastic potential Nuclear
Where is nuclear stored?
Nuclei of atoms
The thicker the arrow in a sankey diagram…
The greater amount of energy
Energy cannot be created or destroyed it can only be…
Transferred from one form to another
What does the first transformer do?
Increases voltage
What does the national grid reduce?
Energy loss during transmission
One unit of electricity is equivalent to what?
One kilowatt used in one hour
Why are power stations built?
To generate electricity
The 1st step in a power station?
Fuel is burned to boil water to make steam
The 2nd step in a power station?
Steam makes a turbine spin
The 3rd step in a power station?
Spinning turbine turns on generator producing electricity
The 4th step in a power station?
Electricity goes to the transformers to produce the correct voltage
The energy needed to boil the water comes from where?
Fossil fuels
Nuclear fuels
What natural renewable ways does the generator directly drive?
Wind and wave power
What is a transformer?
Electrical device that changes the voltage of an alternating current
Name the two transformers?
Step-up transformer
Step-down transformer
Electricity is transferred from…
Power stations to consumers
Some energy is lost through the wire as?
Heat
The higher the current?
The more heat is lost
To reduce heat loss what does the national grid do?
Transmits electricity at a low current, it needs a high voltage
Power stations produce electricity at what?
25,000V
Electricity is sent through the cables at what?
400,000V
275,000V
132,000V
what do step-up transformers do?
Produce high voltages to transmit electricity
What do step-down transformers do?
Used locally, to reduce voltage to safe levels
House hold electricity is?
230V
What is the equation to work out the cost of an electrical appliance?
Energy transferred(kWh) = power (kw) x time (h)
What are fossil fuels?
Coal, oil and natural gas
How where fossil fuels formed?
By remains of living organisms
What do fossil fuels release when burned?
Heat energy
Fossil fuels are…
non-renewable
Name 3 disadvantages for using fossil fuels?
Their supply is limited so they will eventually run out.
Release sulphur dioxide when burned
Release carbon dioxide
Why is carbon dioxide bad for environment?
It adds to the green house effect.
Increases global warming
What is carbon capture?
Prevents carbon dioxide building up in atmosphere
What does carbon capture involve?
Separating carbon dioxide from waste gases
Carbon dioxide is stored where in carbon capture?
Stored underground or under seas
What are the main nuclear fuels?
Uranium and plutonium
What do nuclear fission reactions release?
Heat energy
Disadvantage to wind energy?
Wind farms are noisy.
If there is no wind electricity wont be made
What is a tidal barrage?
A barrier built over a river estuary
Name a power station which doesn’t take long to start up?
Gas-fired station
Name a power station which takes a long time to start up?
Nuclear power station
Optical fibres carry what?
Information coded in light or infrared signals
What is an optical fibre?
Thin rod of high quality glass
Computer data and telephone calls can be converted into what?
Electrical signals
Light getting in at one end does what in an optical fibre?
Undergoes repeated total internal
What are endoscopes?
Images from inside the body
What speed do all electromagnetic waves travel at?
300,00 km/s
Name the electromagnetic waves?
Radio Microwaves Infrared Visible Ultra violet X-ray Gamma
Use of radio waves?
Communication
Use of Micro waves?
Micro-waves
Use of infra-red?
Remotes
Heat
Cooking
Use of visible light?
Fibre optics
Endoscopes
Use of ultra violet?
Forgery marking
Cancer
Use of x rays?
Medical images
Cancer
Use of gamma rays?
Radio therapy
Cancer
