Physics

this is topics one two three

Electricity is an important thing in our everyday life for example: Cooking, stereos 

Electricity is generated in a power station. 

Renewable: It will never run out and can be regenerated 

Non-renewable: It will eventually run out they are finite resources and are non-renewable 

Solar panels - Advantages - They are renewable, It's good for the environment.

Disadvantages - Solar cells only work in the sun so they are unreliable, expensive and they don't produce much energy 

Fossil fuels - Advantages - Fossil fuels are cheap and you get a lot of energy, they are renewable and reliable

Disadvantages - Non-renwable, release carbon dioxide into the atmosphere 

Nuclear Power - Advantages - Nuclear fuels don't produce Co2, Don't escape into the environment, they are reliable 

Disadvantages- Advantages - They produce nuclear waste which is difficult to get rid off, non-renweable and expensive 

Wind- Advantages - The wind is renewable source of energy, low running cost, farmign underneath

Disadvantages - wind turbines can only be in certain places, visual and noise pollution You need lots to create a good amount of energy

Tides - Advantages - low running costs, renewable 

Disadvantages - Tidal power only works on rivers where the water levels changes by a large amount, affects plants & animals 

Hydroelectric schemes - Advanatges - Renewable 

Disavantages - Hydroelectricty needs reservoirs that flood large areas of lan, affecting plants and animals 

Wave power - Wave power uses a renewable energy source and has low running costs

Disadvantages - Lots of wave powered generators would be needed. They might get in the way of ship, unreliable. 

Solar cells >> convert light energy from the sun into electrical energy which can be used in the home  ((Easy to install and maintain, can take the place of of roofing tiles, can be used in inner city areas,renewable,fuel is cheap)) ((Long payback time not always sunny))

Wind turbine >> wind energy converts kinetic energy from the wind moving through the turbine baldes into usegful electrical energy. ((UK is the windiest country in Europe, can produce electricity at rates as good as fossil fuels)) ((planning permission, expensive process, visual and sound pollution, unreliable)) 

Hydroelectric power  converts kinetic energy from a source of free flowing water into electrical energy ((Renewable)) ((got to live by a river, planning permissin expensive to build, land space, unreliable))

All renewable energy resources have carbon footprint because of transport and building costs

Mass = denisty / volume 

mass (kg) 

To find thevolume of some objects you measure a tub of water and then drop the item in claculating how much the water has risen by. 

Objects only float in water if they have a density lower than it which is 1cm3

Water carries more energy than air as it is heavier and would be faster flowing and push the turbine harder and faster. 

Power (W) = voltage x current 

Once electricity has been generated it has to be distrubuted form a large scale power station to our factories and homes. 

The national grid helps do this. It is a network of pylons, cable and transformers which transfers energy from power stations along cables to our factories and homes.

In the winter, mornings and evenings electricty demand is higher and at popular Tv station times e.g. eastenders

If we need more energy neighbouring supplies from countries like France will help when demand is high. 

The step up transformer steps up voltage which means that current decreases so less energy is lost thorugh heat in the wires. Step down transformers decrease voltage and raise current so it useful and safe to use in our factories an dhomes

Cold water is passed trhough  a tube a heated up with fossil fuels such as oil so it turns into high pressured steam this steam then turns a turbine like a wind mill which turns a generator in which electricity is produced. 

Advantages of overhead cables are they are easy to maintain and fix, they are also less expensive but they are visual pollution and people could get seriosuly ahrmed by them 

Energy is transferred to create otehr forms e.g. a light bulb - electrical >> light + heat 

Light is useful heat is not.

Energy = power x time 

TOPICS 4 

Potential energy types - Potential energy is a type of energy that is "hidden" in some way. It is a type of energy that can be converted to other forms and often is related to some attractive or pushing forces.

Gravitational, Elastic, Chemical and nuclear 

Other energy types - Kinetic, heat, light, electricity, sound

Efficiency = useful energy tansfer/total energy imput x 100%

Sankey diagrams represnt the input and output of energy and how much is useful and wasted.

YOU HAVE TO USE A KEY FOR THE DIAGRAM e.g. 1 cm = 10 j 

In order to keep the environment clean and to keep the balance in the gases around us we have to be efficent, especially in power staions. There has to be as little wasted energy as possible so that less resources are wasted like oil which is limited and carbon footprint stays low and global warming id reuced and/or kept to mimimum.

Heat is transferred in three main ways 

• convection (liquids & gases) 
• conduction (solids) 
• radiation (all three) 

Heat energy always moves in the same direction, from warm to cold. 

CONDUCTION 

Conduction is the process in which vibrating particles pass on their vibration energy from hot to codl through the solid. 

Metals are good conductors of heat and electricty so: Aluminimum, Copper, iron & silver

CONDUCTION 

Conduction is the process in which vibrating particles pass on their vibration energy from hot to codl through the solid. 

Metals are good conductors of heat and electricty so: Aluminimum, Copper, iron & silver

Non metals are bad conductors and are good insulators e.g. Plastic, wood, rubber, glass

Convection (liquids) 

Convection current can be shown in a diagram of a pan of boiling water heat comes from the gas falme which heats the bottom rising to the top where hot water cools and then falls and gets warmed again before rising as it beocme a continous cycle 

Convection cannot take place in a solid as solids particles can only vibrate where as conduction needs free flowing particles 

The heating element of a kettle is ayt the bottom as hot water particles rise not fall and when you pour in the water it settles at the bottom rather than the top 

Convection (gases)

The air is heated by a source e.g. candle and it rises that air is replaced by cool air which falls and gives the source more oxygen to burn or gets heated.

A sea breeze takes place because the land is warmer than the sea so when the land warms up the air above the sea waves take the place of the warm air that rises creating a cool breeze. 

Radiation is not like ocnduction and convection as it can travel through anything including a vacuum or any transparent material. It travels at the speed of light and is invisible. Some objects absorb radiation where as others reflect it.

Heat radiation is emitted by hot object in all direction 

Good emitters of heat radiation are normally like dull,black colours and surfaces like an aga 

these black surfaces and materials also absorb heat they are poor reflectors.

Shiny light surfaces are good emmiters and poor absorbers and poor absorbers but good reflectors 

Air is an insulator becasue it can warm up and traps heat. This is especially productive in small pockets of air which can be found is cavity wall insulation. Feathers, cotton wool, bubble wrap and foam all have trapped air in them. Small pockets of air are used as then the air can't move and it reduceds the possibilty of convection 

Trapped air within a material does not stop radiation only shiny light materials can do this which air is not 

Drink falsks have vacuums to stop heat loss through convection and conduction 

Victims in accidents are wrappedin foil blankets to stop heat loss through radiation and so the heat bounces back into or onto the body

Teapots have cosies to insulate them and keep the tea (liquid) warm 

Heat is lost in houses through various situations and it can be stopped or prevented or reduced.

Heat can be lost through windows, doors, gaps, the ground and roofs 

You can reduce heat loss through the roof by adding roof insualtion 

Draughts by draught excluders and windows thorugh double glazing 

PAYBACK TIME = cost / annual savings 

Insulation in walls can recude conduction convection and radiation by trapped air stopping conduction in small pockets the foam stopping convection and radiation being stopped by shiny material wrapped around the foam wwhich would emit the heat back into the house. 

If everyone insulated their house and stopped wasting energy less fuels and electricity would be used to heat the house therefore reducing the effects of global warming

TOPIC 5 WAVES

waves are caused by vibrations which travel outwards from the source of the vibration, transferring energy as they travel.

Heat waves, Sound Waves, Gamma waves, Radio waves

Wavelength is the distance between two consecutive points in a wave e.g. crest to crest, troph to troph or peak to peak

Amplitude is half the waves height the bigger the amplitude the more energy a wave carries 

Frequency is the number of waves passing a point per second. 

Speed of waves is how mast the wave travel. Units are m/s or ms-1 

Red monkeys invented very useful Xray goggles

Radio, microwave, infra red, visible, uv rays, X ray, gamma 

Visible light can be detected by the human eye 

Radio has the longest wavelength and the longest frequency  Gamma rays have the shortest wavelength and the highest frequency. All these waves travel at the speed of light.

They all travel in straight lines 

They can all travel through a vaccum 

All invisble to the naked eye bar visible light 

The lower the wavelength the higher the frequency, the higher the frequnecy the more dangerous it is to the human body 

Radio, micro, infra red and visible light rays can all be used in communcation and to carry large amounts of information 

Visible light rays are emitted from the the sun and enter our earth this then bounces of or reflects objects including the Earth's surface but become longer in frequency as infra red rays. These get trapped causing th enatural affect of the green house affect using gases such as carbon dioxide, this warms the atmosphere.This is a natural process but Co2 levels have increased due to the rapidly increasing use of burning fossil fuels

Mobile Phone - Mobile phones transfer info over large distances using microwaves from one person to mast to a second person. They are clean, clear and have low infrastructure but can cause brain tumour and the signals have to be in range of a mast. 

Satellite links - A satellite which stays in the same place over earth. A person signal is sent from a mast to a satellite and back down to another mast to anotehr isgnal.It gives constant coverage and GPSS sattelite TV but its is expensive difficult to position and high amount of technology with a risk of crashing. 

Fibre optics - Fibre optic is a glass cable that transfers light signals over long distances. The advantages a they are hard to tap into and they carry large amounts of information but are breakable hard to maintain as under gorund, it is hard to place these cables. telephone to fibre optic link to telephone. 

Atoms are made up of protons neutrons and electrons. The nucleus contains postively charged protons and neutrons and orbiting negatively charged electrons. It comes from the Greek meaning cannot be split. 

The mass number is the number of protons and neutrons and the atomic number is the number of protons which is the same as the number of electrons. To find out the number of neutrons you minus the atomic number from the mass number. 

Ionization is the change in an atom or molecule into a charged particle usually by losing or gaining an electron 

Ionising radiation is the higher energy electromagnetic radiations. Namely these are UV, X- rays and gamma rays. They can be very useful but also very dangerous

Background radiation is the radiation that is around us at all time and is found in rocks and soil as a product known as radon. It can be removed from homes using a radon sump and can be prevented with good ventilation floor insulation so it can't get through and be checked using a radon meter.

Cosmic rays come from the stars and the sun

Alpha: back to front fish, highly ionizing lowly penetrating found in radon. Has two protons and two neutrons which makes a helium nucleus. Stopped by a few cm of air or thin piece of paper 

Beta: B with a long stick, medium ionizing and medium penetrating, a fast moving electron. Produced by radium isotopes. Stopped by aluminium or perspex 

Gamma: A fish on a wave with an arrow at the end. Is a high energy Em wave and can be produced by fission of uranium. Stopped by lead or steel bars in concrete

They are cut down and boiled in nitric acid then mixed and melted with glass which is then poured into lead lined steel containers and stored under ground for many years until the waste become un-reactive. 

To protect people who work with nuclear power and waste they use masks protective clothing stand behind sheets of lead 

Nuclear waste is produced in nuclear power plants hospitals and dentists