Physics P1

• Coal (Atmospheric, visual, waste & noise pollution) [near coal mines]
  
• Oil (Atmospheric, visual, waste & noise pollution) [near the coast]
  
• Natural Gas (Atmospheric, visual, waste & noise pollution) [anywhere there is piped gas]
  
• Nuclear Fuels eg. uranium/plutonium (Atmospheric, visual, waste & noise pollution, AND dangerous) [away from people and near water]
  

They will all run out one day. They all do damage to the environment. BUT>>> They provide most of our energy.

Power Stations:  A fossil fuel is burt to convert the chemical energy into heat energy. The heat energy is used to heat water/air to produce steam. The steam turns the turbine, which turns it into kinetic energy. The turbine is connected to a generator, which transfers kinetic energy into electrical energy.

A nuclear power station is similar to a power station. However, they have a nuclear fission of urnaium/plutonium to produce the heat to make the steam to turn the turbines.

Nuclear power stations take the longest time to start up, while natural gas power stations are the quickest.

• Wind [exposed, windy places like moors and coasts or out at sea]
  
• Waves [on the coasts]
  
• Tidal [near big river estuaries where a dam can be built]
  
• Hydroelectric [hilly, rainy places with floodable valleys]
  
• Solar [pretty much anywhere]
  
• Geothermal [fairly limited only in places where hot rocks are near the Earth's surface]
  
• Food
• Biofuels

They will never run out. Most do damage, but not as much as the non-renewable sources. BUT>>> they don't provide as much energy and are unreliable as they depend on the weather.

Wind turbines are put in exposed places like moors or around coasts. Each turbine has a generator inside. The electricity generated is directly from the wind turning the blades, powering the generator. There is no pollution, but they spoil the view. Also, you would need 1500 wind turbines to replace 1 coal power station. They can be very noisy, which is irritating for people living nearby.When the wind stops there is no power, and you cannot increase supply, when there is more demand. The intial costs are high, but the running costs are very low. There is no permanent damage to the landscape as removing the turbines gets rid of the noise and view pollution. (Visual & noise pollution)

The generate electric currents directly from sunlight. They are the best source of energy for watches and calculators, which don't use much energy. It is used in remote places where there isn't much choice and to power road signalsand satellites. There is no pollution, but the initial costs are high. However, the energy is free and the running costs are low, They generate electricity on a relatively small scale, e.g. powering individual homes. It's too expensive to connect them to the National Grid.

It requires flooding a valley by building a dam. Rainwater is caught and allowed out thorugh turbines. There is no pollution, but there is a big impact on the environment, due to the flooding as rotting vegetation releases methane and CO2. There is also a possible loss of habitat for some species. They can also look unsightly when they dry up. Putting these power stations in remote valleys lessens the impact on on humans. It can provide an immediate response to increased demand in electricity. There is no problem of reliability, except in timjes of drought. Initial costs are high, but there are no fuel or running costs. It can be a useful way to generate electricity on a small scale in remote areas. (Visual pollution AND disruption of habitats AND bursting dams)

You need lots of small wave-powered turbines located around the coast. As waves come into the shore they provide an up and down motion, which can be used to drive a generator. There is no pollution. The main problems are spoiling the view and being a hazard to boats. They are quite unreliable, because waves tend to die out when the wind drops. The initial costs are high, but there are no fuel costs and minimal running costs. Wave power cannot provide energy on a large scale, but it can be very useful on small islands. (Visual pollution AND disruption of leisure activities)

They are big dams built across river estuaries, with turbines in them. As the tide comes in it fills up the estuary to a height of several metres, which also drives the turbines. The water can then be allowed out through the turbines at a controlled speed. The source of the energy is the gravity of the Sun and the Moon. There is no pollution. The main problems are preventing free access by boats, spoiling the view, and altering the habitat of the wildlife. Tides are pretty reliable, because they happen twice a day without fail, and are always near to the predicted height. The only drawback is that the height of the tide is variable so lower "nep" tides will produce significantly less energy than the bigger "spring" tides. They also don't work if the water level is the same either side of the barrage, but they are excellent for storing energy ready for periods of peak demand. The initial costs are moderately high, but there are no fuel costs and minimal running costs. (Visual AND disruption of habitats and leisure activities)

This is only possible in volcanic areas where hot rocks lay near to the surface. The source of the heat is from slow decay of various radioactive elements deep inside the Earth. Steam and hot water rise to the surface and drive a generator. This has no real environmental problems, and is free. The main drawback is that there aren't many suitable locations for the plants. Also, the cost of building the plant is higher than the amount of energy we can get out of it.

They are renewable energy resources. They are used to generate energy in exactly the same way as fossil fuels, they're burnt to heat up water. They can also be used in some cars. They can be solids, liquids or gases. We get get them from organisms that are still alive, or from dead organic matter.

They are reletively quick and "natural" sources of energy and are supposedly carbon neutral. However, once the full energy that goes into the production is considered, the imapct of biofuels is considered. In some regions, there have been cases of deforestation to make room to grow biofuels, resulting in many species losing their natural habitats. The decay and burning of the vegetation increases carbon dioxide and methane emissions. They have potential, but their use is limited, because of the amount of available farmland that can be dedicated to their production.

Heat is transferred in 3 ways - Radiation (by infra-red, solids liquids and gases), Conduction (kinetic theory, solids), Convection (particles, liquids and gases). The bigger the temperature difference between an object and its surroundings, the faster energy is transferred by heating.

Infra-red Radiation: Hotter objects emit more radiation than they absorb (cooling down). Cooler objects absorb more radiation than they emit (warming up). Dark, matt surfaces absorb and emit radiation better, while light, shiny surfaces reflect radiation to retain heat.

Conduction: of heat energy is the process where vibrating particles pass on their extra kinetic energy to neighbouring particles. Heating a substance gives the particles more energy, meaning they can move/vibrate faster. Metals are good conductors, because of their free electrons - they can move around.

Convection: occurs when the more energetic particles move, taking their heat energy with them, from the hotter region to the cooler region. It is about the changes in density:

Liquid/gas (l/g) heats - Hot l/g less dense - Less dense l/g rises - Faster particles collide with slower particles & transfer heat - L/g cools becomes less dense - Denser l/g sinks.

Condensation is when a gas turns to a liquid. When a gas cools down, it moves slower and loses kinetic energy. The attractive forces between the particles pull them closer together. If the temperature is cold enough and the particles are close enough, condensation takes place and the gas turns into a liquid.

Evaporation is when a liquid turns into a gas. Particles can evaporate from a liquid at temperatures that are lower than its boiling point. The particles near the surface of a liquid can escape and become gas particles if the particles are travelling: 1) in the right direction, 2) fast enough to overcome the attractive forces of the other particles.

Condensation will be faster if: 1) TEMPERATURE of the gas is lower, 2) TEMPERATURE of the surface is lower, 3) DENSITY is higher, 4) AIRFLOW is less.

Evaporation will be faster if: 1) TEMPERATURE is higher, 2) SURFACE AREA is larger 3) DENSITY is lower, 4) AIRFLOW over the liquid is greater.

The rate of heat energy depends on many things. The bigger the surface area, the more infra-red can be emitted/absorbed by the surface, so the quicker the transfer of heat. If two objects at the same temperature have the same surface area but different volumes, the smaller volume object cools more quickly, because a higher proportion of the object is in contact with its surroundings. The material can affect the rate too. Objects made of good conductors transfer heat more quickly than insulating materials. If the object is in contact with a good conductor, the heat will be conducted faster than being in contact with a good insulator.

Vacuum Flasks: Silver double-walled glass bottle, with a vacuum between walls, which stops conduction & convection through the sides and keeps heat loss by radiation to a minimum. Supported using insulating foam, which minimises heat conduction to/from the outer glass bottle. Plastic stopper filled with cork or foam to reduce any heat conduction through it.

Humans and animals. Cold: hairs/fur rises up limiting convection heat loss (thicker layer of insulating air around the body). Hot: bodies divert blood flow near to the surface of skin to lose heat by radiation. Animals in warmer climates have larger ears than lose in colder climatees to help to control heat transfer.

Payback time = inital cost / annual saving.

The most cost-effective methods of insulation are the ones which give you the biggest annual saving. They tend to be the cheapest, and they have a short payback time.

CAVITY WALL INSULATION: foam is squirted into the gap between bricks, which stop convection currents setting up and radiation across the gap. The air pockets trapped in the foam reduces heat loss by conduction too.

LOFT INSULATION: a thick layer of fibreglass wool is laid out across the floor, which reduces conduction and radiation.

DRAUGHT-PROOFING: strips of foam and plastic are put around doors and windows to stop draughts of cold air blowing in, which stops heat loss by convection.

HOT WATER TANK JACKET: reduces conduction and radiation.

THICK CURTAINS: big bits over cloth over the window, which reduces heat loss by conduction and radiation.

E = m X c X θ

E --> Energy transferred (J) m --> Mass (kg) c --> Specific heat capacity (J/kg°C) θ --> Temperature Change (°C)

Specific heat capacity tells you how much energy stuff can store. Equation above.

9 types of energy:

ELECTRICAL, LIGHT, SOUND, KINETIC/MOVEMENT, NUCLEAR, THERMAL/HEAT, GRAVITATIONAL POTENTIAL, ELASIC POTENTIAL and CHEMICAL energy.

These are forms of stored energy.

Conservation of Energy Principles: Energy can be transferred usefully from one form to another, stored or dissipated - but it can never be created or destroyed. Energy is only useful when it can be converted from one form into another.

Most energy transfers involve some losses, often as heat from the input energy. A device that wastes the least energy, is more efficient. EFFICIENCY = useful energy or power out / total energy or power in.

Useful energy is concentrated energy. Waste energy is usually heat, which is transferred to cooler surroundings and the energy slowly dissipates. The total amount of energy is the same, but it is hard to easily use it or collect it back in again.

Heat exchangers reduce the amount of heat energy that is wasted, by pumping a cool fluid through the escaping heat. The temperature of this fluid rises as it gains heat energy. The heat energy in the fluid can then be converted into a form of energy that can be useful either in the original device or for other functions.

Energy (J) = Power (W or kW) X Time (secs/mins/hrs)

kWh (Kilowatt-hours) are units of energy, which is the standard unit of electrical energy.

Cost of Electricity Formulas:

Units (kWh) = Power (kW) X Time (hrs)     or     Cost = Units (kWh) X Price (per unit)

Electricity Meters:

They are in kWh. You may need to figure the total energy used over a certain time period, so yo will need to ensure that you subtract the start value from the end value.

All 3 fossil fuels release CO₂ into the atmosphere when they're burned. All the CO₂ adds to the greenhouse effect, which contributes to global warming. Burning coal and oil release sulphur dioxide, which causes acid rain, however this can be reduced by taking out the sulphur beforehand or by cleaning up the emissions. Coal mining can mess up the landscape. Oil spillages cause serious environmental problems. Nuclear power is clean, but the nuclear waste is very dangerous and difficult to dispose of. Nuclear fuel is relatively cheap, but the overall cost of nuclear power is high, becasue of the cost of the power plant and the final decommissioning. Nuclear power also carries the risk of a major catastrophe, such as the Chernobyl disaster in 1986.

Carbon capture and storage can reduce the impact of CO₂. It collects the CO₂ from power stations, before it is released into the atmosphere. The captured CO₂ can be pumped into empty gas fields and oild fields like those under the North Sea. It can be safely stored without it adding to the greenhouse effect. It's a new technology that's developing quickly. New ways of storing CO₂ are being explored including storing CO₂ dissovled in seawater at the bottom of the ocean and capturing CO₂ with algae, which can then be used to produce oil that can be used as a biofuel.

SET UP COSTS:

Renewables havebigger power stations thannon-renewables, menaing they'remore expensive. Nuclear &hydroelectric also need a lot of money to ensure that they aresafe.

RELIABILITY ISSUES:

Non-renewables arereliable (until they run out).

RUNNING/FUEL COSTS:

Renewables have the lowest running costs, because there's no actual fuel involved.

Electricity is distributed via the National Grid. It takes electrcity from the plants to homes and industry. You can generate electricity anywhere on the grid, and supply it anywhere on the grid. To transmit the high amount of power, you need to have either a high voltage or a high current. Having a high current means that you lose a lot of energy through heat in the cables.

You can use pylons and transformers to get the voltage higher. The pylons need to have huge insulators, even though they are expensive, it is cheaper to have them than to have a high current. From the power station, a step up transformer makes the voltage higher, for efficient transmission. A step down transformer makes the voltage lower so that it can be delievered at safer levels.

You can transmit electricity thorugh overhead cables or underground cables. They each have their own pros and cons.

The National Grid needs to make sure that the supply of electrcity matches the demand of electricity. Supply can be increased by opening more power stations, or by increasing their power output. Demand can be reduced by consumers using more energy-efficient appliances.

Waves have amplitude, wavelength and frequency. Transverse have sideways vibrations --> the vibrations are perpendicular to the direction of energy transfer of the wave. Longitudinal waves have vibrations along the same line --> the vibrations are parallel to the the direction of energy transfer of the wave.

Wave Speed (m/S) = Frequency (Hz) X Wavelength (m)

All waves can be reflected, refracted or diffracted. Reflection of light lets us see things. When light travelling in the same direction reflects from an uneven surface, such as a piece of paper, the light reflects at different angles. When light travelling in the same direction reflects from an even surface, its all refelcted at the same angle. ANGLE OF INCIDENCE = ANGLE OF REFELCTION.

Drawing a Ray Diagram:

• The image is the same size of the object
• It is AS FAR BEHIND the mirror as the object is in front
• The image is vertical and upright
• The image is laterally inverted (left and right swapped)

Diffraction is when waves spread out when they pass through a gap. If the gap is much wider than the wavelength, there is little diffraction. If the gap is a bit wider than the wavelength, there is only diffraction at the edges. If the gap is the same size as the wavelength, you get the maximum diffraction.

Refraction is when you change the speed of a wave, which changes its direction. For example, when a wave crosses a boundary between two substances it can change direction. If the wave hits the boundary "face on", then it carries on in the same direction. But if a wave meets the substance at a different angle, then it changes direction, and is refracted.

Gamma, X-ray, Ultraviolet, Visible light, Infrared, Microwaves, Radiowaves. (Smallest to Largest)

Radiowaves are used for communication. Theu have wavelengths that are longer than about 10cm. Long-wave radiowaves can diffract around the curved surface of the Earth and reach aobut halfway around the world. They can diffract around hills and into tunnels. This allows the reciever to get the wavelength even if they aren't in direct sight of the transmitter. Short-wave radiowaves can also be recieved at long distances, because they are reflected fromthe ionosphere (an electrically charged layer in the Earth's atmosphere). Medium-wave signals can also reflect from the ionosphere, depending on the time of day and atmosphereic conditions.

Microwaves are used for satellite communication and mobile phones. They can get through the Earth's watery atmosphere. A signal is sent to the satellite, which is then transmitted back to the Earth in a different direction, where it is recieved by a satellite dish on the ground.

Infrared waves are used for remote controls and optical fibres. The signal is sent as pulses of light or a patterns.

Visible light is good for photography as you can see what you are photographing.

Sound travels as a wave, which is caused by vibrating objects. They are a type of longitudinal wave. It travels faster in solids than liquids, and faster in liquids than gases. Sound can't travel in a vacuum, because there are no particles.

Sound waves can reflect and refract. They are reflected by hard flat surfaces. They are refracted when they cross into a different substance. In denser substances, they speed up.

The higher the frequency, the higher the pitch. The frequency is the number of complete vibrations each second. High frequency/pitch, means shorter wavelength. The volume of the sound depends on the amplitude of the sound wave. Bigger amplitude = louder sound.

The universe seems to be expanding:

1) Light from other galaxies is red-shifted. When looking at light from distant galaxies, we see that the frequency is slighty lower than what it should be - they have shifted towards the red end of the spectrum, which is called red shift. Its the same effect as an ambulance going past you. The sound begans high-pitched, but when it has passed you an is mobing away it is more low-pitched. This is called the DOPPLER EFFECT. This can happen with transverse and longitudinal waves.

2) The further away a galaxy is the greater the red shift. Measurements of the red-shift suggests that all of the galaxies are moving away from us very quickly. Closer galaxies are moving slower than further away galaxies.

The universe began with a Big Bang. This theory states that all the matter and energy in the universe was compressed into a small space, and it then exploded from this point and started expanding. The expansion is still happening, and we can estimate the age of the universe to be about 14 billion years old. The discovery of CMBR was also good evidence that the Big Bang was more likely than the Steady State Theory --> the universe has always existed the way it is now and always will.