Physics 1b Flashcards
What are the four types of non-renewable energy resources ?
Coal
Natural gas
Oil
Nuclear
What are the renewable energy sources ?
Wind Wave Tidal Hydroelectric Solar Geothermal Biofuels
How does oil generate electricity ?
- Fossil fuel burnt, converting chemical energy to heat.
- This heats water and turns it into steam
- The steam turns a turbine, converting heat to kinetic energy
- A generator converts the kinetic energy to electrical energy
What are the disadvantages of wind power ?
Some consider them an eyesore
Sound pollution
No power when the wind stops so unreliable
How do wind turbines work ?
A generator converts the kinetic energy of the wind blowing the blades into electrical energy
What are the disadvantages of hydroelectric power ?
- Valleys flooded which damage environments
- People are moved out of their homes to make way for the dams
- High initial costs
What is a new way hydroelectric dams work when it’s not raining so much ?
There is a second ‘lower reservoir’ and a pump which keeps the higher reservoir full
How do tidal barrages work ?
They are basically bridges built across an estuary that has turbines inside them, generators convert the kinetic energy to electrical energy
True or false- biofuels work in the same way as crude oil does
True - they heat steam which turns a turbine
What is geothermal energy ?
Water is pumped down deep under ground where the heat from the rocks turns the water to steam when it comes back up. Then the steam turns a turbine and then that turns a generator.
What is a major drawback of geothermal power ?
You need to be in very specific locations and it is very expensive
Other than burning fossil fuels, how are non renewable energy sources bad for the environment ?
- Coal mining makes a mess
- oil spillages damage sea wildlife
- nuclear waste is extremely dangerous
- nuclear disasters like Chernobyl
- burning any fuel gives off CO2 (causes global warming) and SO2 (causes acid rain)
True or False - non renewable set up cost are higher than renewable
Why ?
False - renewable energy sources need bigger power stations therefore cost more
What is carbon capture ?
Carbon capture is when you collect the CO2 before it is released into the atmosphere. It is then pumped into empty oil fields (caves underground) and therefore doesn’t contribute to the greenhouse effect
Who distributes electricity to the country ?
National grid
What do step up transformers do ?
Increase the voltage so that it can be distributed across the UK - this reduces the current so there is very little power lost due to heating the wires.
What do step down transformers do ?
Bring down the voltage to safe usable levels
Why are some cables now put under ground ?
It is more reliable / unaffected by weather / minimal maintenance / hidden away
What is the amplitude of a wave ?
Height from rest position
What is wave length ?
The length of a full cycle
What is the frequency ?
The amount of complete waves passing a certain point in a second
What is a transverse wave ?
In transverse waves the oscillations are perpendicular (90 degrees) to the direction of energy transfer.
What waves are transverse ?
EM spectrum
Ripples on water
What are longitudinal waves ?
In longitudinal waves the oscillations are parallel to the direction of energy transfer
What is the equation for wave speed ?
Frequency (Hz) x wavelength (m)
What is a reflection ?
What is the reflection of sound called?
Reflection is when a wave bounces of an object at the same angle of incidence.
Echo
What is the law of reflection ?
Angle of incidence = angle of reflection
What is diffraction ?
When a wave spreads out at the edges when they pass through a gap
If the gap is wider than the wavelength, what happens ?
Little diffraction
If the gap is slightly wider than the wavelength, what happens ?
Diffracts only at edges
If the gap is the same as the wavelength, what happens ?
Maximum diffraction
What is refraction ?
When a wave crosses two boundaries ( from gas to air, say) it changes direction
Why do waves refract ?
When the wave hits a different medium ( material ) the density the wave travels through changes so they change speed.
What is the emergent ray ?
The wave that leaves the medium it entered
In order (highest to lowest frequency), what are the 7 waves on the EM spectrum ?
Gamma X-ray Ultra violet Light Infra red Micro waves Radio waves
What are microwaves mainly used for ?
Satellite communication
Eg. Text messages and phone calls
What are infra red waves used for ?
Remote controls
How does visible light work in cameras ?
Cameras have lenses to focus visible light onto a light sensitive film or electronic sensor
Why do echoes occur
They are reflected sound waves
The pitch is higher when the frequency is …………. .
Higher
The bigger the amplitude the ………… the sound.
Louder
What is the Doppler effect ?
When something is moving towards the waves are squashed together so they have a higher pitch, when they go away from you the waves are spread out behind the object and so the pitch is lower.
What happens if a car travels towards you ?
The frequency increases and the wavelength decreases.
This is because as the car moves forward he waves at the front are pushed together
How does red shift give evidence for the universe expanding ?
Measurements of red shift shows that galaxies further away are moving quicker than galaxies near to us. This shows that more distant galaxies are expanding and therefore so Is the universe
What is the Big Bang theory ?
The theory that all the energy and matter was compressed into a very small space. This then exploded and expanded, it is still expanding now. It is currently guessed that the universe was created 14 million years ago
What is steady state theory ?
The idea that the universe has always been as it is now except galaxies pop in and out of existence.
What is ‘cosmic microwave background radiation’ ?
It is a low frequency electromagnetic radiation coming from all parts of the universe. It was initially gamma waves when the big bang occurred but now it is microwaves - it has been red shifted all the way to the other end of the EM spectrum
How did CMBR help explain the Big Bang theory ?
The CMBR waves were found to be everywhere in the universe and spread out evenly. If you combine this with red shift and rewind time - it all must have started from the same point.
What is red shift?
It is when the light given off from a galaxy is shifted to the red end as it is moving away from the Earth.
This is noticed because each element will give off a unique spectra of colours (think of it like a barcode). When it is red shifted the spectra moves to the red end of the spectrum and the galaxy appears to be giving off different colours.
What is total internal reflection and what is it used in?
When light is reflected down an optical fibre.
It is used in endoscopes in medicine and fibre optic broadband.
Why does red shift support the big bang theory?
Red shift states the universe is expanding. If you reverse time then red shift shows us that the universe must have started as one point.
Why may people not believe the big bang theory?
There is only supporting evidence, there is no way of going back in time to see it.
Religion is not taken into account.
What are the advantages and disadvantages of placing telescopes in space?
Advantages
No atmospheric interference
Can look at the starts all the time
Disadvantages
Costs a lot of money
Impossible to repair if they break
