F P1 JM

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Physics 1: Revision Solid Liquid Gas Kinetic Theory There are 3 states of matter: Solid Liquid Gas Particles arranged in fixed positions Particles vibrate in position Particles are free to move over each other Takes the shape of its container Increased Density Particles are free to move any direction Particles move at high speeds

There are 9 different forms of energy: Light Thermal (heat) Kinetic (movement) Chemical Elastic Potential Electrical Sound Nuclear Gravitational Potential Energy is never created or destroyed! This is called the conservation of energy. Energy is only ever transferred from one form to another (e.g. kinetic to sound) Not all of the energy transferred by a device is useful energy. Non-useful energy can be called wasted energy

Sample Question (taken from 2011 specimen paper):

Sankey diagrams and efficiency Sankey diagrams are ways of representing the different energy transformations that take place in different electrical devices. The start of the sankey diagram shows the total energy going into the device. The diagram then splits off into different sized arrows to represent the other energy transfers that take place, the bigger the arrow the larger the energy. The energy entering the device must equal the energy leaving the device. Sample sankey diagram for a light bulb

To know how good a device is at transferring energy you need to be able to calculate the efficiency. To do that you need to use the following equation (which will be given in the exam) So for the example sankey diagram (on the previous page) the answer would be: The closer the efficiency is to 1 the more useful energy the device is transferring. So for the light bulb example we got an efficiency of 0.1, so the light bulb isn’t very good and transferring useful energy. To get a percentage, all you do is multiply the efficiency number by 100.

Sample Question (taken from 2011 specimen paper):

U-Values U-values are used in Europe to describe the properties of building materials. They tell us how well a material allows energy to be transmitted through it. For instance, different types of glass can have different U-values. When building a house, the U-value of the windows should be taken into consideration because you’d want to minimise heat (energy) loss. The higher the U-value, the better it is at transmitting energy – not good for insulation. Lower U-values insulate better because they allow less heat through them.

Sample Question (taken from 2011 specimen paper):

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Heat Transfer Heat can be transfer by 3 methods: Conduction: Occurs in solids and felt by direct physical contact. Convection: Occurs in liquids and gases. Hotter part rises, cooler part sinks. Radiation: All objects do it. Can travel through empty space (vacuum) and travels in waves. You can prevent heat loss from objects by using insulation. Air is a bad conductor of heat but makes a good insulator. For convection you must stop the heat from rising (e.g. using a lid) Trapped air helps to prevent heat loss by conduction and convection. Radiation can be reduced by using light reflective surfaces. REMEMBER: Black is a good absorber and emitter of radiation but light and reflective surfaces are bad absorbers and emitters.

Sample Question (taken from 2011 specimen paper):

Sample Question (taken from March 08 [old spec] paper):

Sample Question (taken from 2011 specimen paper):

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Specific Heat Capacity Specific heat capacity refers to the amount of energy needed to raise the temperature of 1kg of a substance by 1°K. Kelvin (K) is exactly the same as Celsius (C) in this instance. If you go up 1K, you go up 1°C. The unit of SHC is J/Kg-1K-1 or J/Kg-1°C-1 Different substances have different specific heat capacities. Water has a SHC of 4200 J /Kg-1K-1 This means it takes 4200J to raise 1kg of water by 1K Using the specific heat capacity, we can work out the energy transferred to heat the substance and raise its temperature when we have larger masses of the substance and greater changes in temperature. You’ll be given the equation in the back of the exam paper, but will have to substitute in values that the exam qestion gives you.

E = m x c x θ E = 705,600 J E is the amount of energy required m is the mass of the material c is the specific heat capacity of the material Θ is the change in temperature (K) Example of a question Calculate the energy needed to raise the temperature of 14kg of water by 12K E = 14 x (4200) x 12 E = 705,600 J Sample Question (taken from 2011 specimen paper):

Generating Electricity Electricity is usually generated by burning a form of fuel to heat water. This water then turns to steam The steam then spins the turbine The turbine is connected to a generator The generator creates electricity and travels to a transformer where the voltage is “stepped up” or increased (to around 40,000v) for efficiency The electricity then travels down the electrical lines and then gets “stepped down” by another transformer (to 240v) and enters the home. 5

Nuclear Power Stations We can also change the thing that heats the water in the power station In a nuclear power station the heat comes from a radioactive process called nuclear fission. This produces LOADS of thermal energy, which can then be used to heat water. The benefits of this are that nuclear does not release any greenhouse gases like burning fossil fuels does. However, it does create vast amounts of toxic radioactive waste that is difficult to dispose of (usually buried) and poses a risk of radioactive leaks, like Fukushima in Japan

Sample Question (taken from 2011 specimen paper):

Generating Electricity We can also change the thing that heats the water. In a nuclear power station the heat comes from a radioactive process called nuclear fission. This produces LOADS of thermal energy, which can then be used to heat water. The benefits of this are that nuclear does not release any greenhouse gases like burning fossil fuels does.

Power and electricity bills Power is measured in watts (W) and it is the amount of energy transferred in one second. So a 60W bulb transfers 60 Joules of energy every second. To know how much electrical energy you have used, you need to multiple the power of the device by the number of hours it has been on for. So if the bulb has been on for 5 hours then it has use 300 Watt-hours of energy. However, the electricity companies use kilowatt-hours (kWh) to work out your bill. So the bulb would then have used 0.3 kilowatt-hours of electrical energy.

Electricity companies charge you for every kilowatt-hour of electricity you use. So, for example, if an electricity company changes you 10p per kilowatt-hour of electricity used then the bulb has cost you: The present cost for a unit of electricity from E-on is 17.13p How much would the bulb cost today for the same amount of time? (2 marks)

Sample Question (taken from 2011 specimen paper):

Energy resources Electricity can be generated from several different resources such as wind, water, fossil fuels, light and nuclear. Some are renewable (can be used again) and other are non renewable. Fossil fuels are fuels which were made from plants and animals that lived millions of years ago. Examples of these fuels are coal, oil and gas. Fossil fuels need to be burned in order to be used to generate electricity. This is also true for biomass. The other energy resources don’t need to be burned to work but they do involve making a turbine spin except for solar. For solar energy the light gets converted directly into electricity.

Nuclear (fuel is uranium/plutonium) Energy type Renewable Causes acid rain Causes global warming Reliable (will always work) Other info Wind YES NO Free energy source Wave Solar Geothermal Free energy source, Creates steam Fossil fuels Needs burning Nuclear (fuel is uranium/plutonium) High decommissioning (dismantling) costs, produce radioactive waste, no other pollution Hydroelectric Free energy source, Good for sudden electricity demand Biomass Tidal

Wave speed can be calculated using the following equation: Wave Properties The amplitude of a wave refers to the height of a wave. The frequency is the number of waves that occur every second. The frequency is measured in Hertz (Hz). 1sec 3 waves in 1 second 3Hz The wavelength the distance between one point on the wave to the next corresponding point, measured in metres (m). The easiest way to think of it is the distance between one peak and the next peak - this is one complete wave. Wavelength Wave speed can be calculated using the following equation: Wave = Frequency x Wavelength Speed (m/s) (Hz) (m) Wave Speed (m/s) Frequency (Hz) Wavelength (m)

Sample Question (taken from 2011 specimen paper):

Properties of Waves In transverse waves the oscillations are perpendicular to the direction of energy transfer. In longitudinal waves the oscillations are in the same direction as the energy transfer. Sound waves are a great example of where we experience longitudinal waves Sample Question (taken from 2011 specimen paper):

Reflection, Refraction and Diffraction Reflection is when waves “bounce off” a surface or substance. In reflection, the angle of the reflected wave is identical to the incident angle. Refraction is when a wave changes direction at the boundary of a new substance. Light travelling from air into water will refract. Diffraction is the “spreading out” of waves when they pass something or travel through a gab. Diffraction is most noticeable when the gap size is similar to the wavelength of the waves Waves not diffracted enough by the hill for the house to receive a TV signal

EM Spectrum, The electromagnetic spectrum is energy that travels by waves. The only part of the spectrum that we can see is visible light. The electromagnetic spectrum has different properties, namely frequency and wavelength. Part of the spectrum Frequency (Hz) Wavelength (m) Gamma Highest   Lowest Shortest Longest X-ray Ultraviolet Visible Infrared Microwave Radio

EM Spectrum, All electromagnetic waves travel at the same speed in a vacuum (empty space). You can calculate the speed of a wave (measured in metres per second [m/s]) if you know the frequency and the wavelength. All EM waves can be reflected, refracted and diffracted The visible part of the spectrum can be broken up also. The light that we see can be separated into the colours that compose white light. This can be done by passing light through a prism. A very common example of light getting separated is a rainbow, when light passes through raindrops.

Part of the spectrum Advantages Disadvantages Gamma To sterilise surgical instruments To kill cancer cells High doses can kill cells Low doses can cause cancer X-ray To see bones Ultraviolet In sun beds to give a tan Identifying forgeries in money Low doses can cause cancer (skin) Visible For seeing and communication - optical fibre broadband Blindness Infrared Communication e.g. remote control for TV For cooking e.g. toaster Absorbed by skin and felt as heat Excessive amounts cause burns Microwave For communication in mobile phones and with satellites Cooking food Absorbed by water in the cells, releasing heat, this can damage or kill the cells Radio For communication without the use of satellites High levels can lead to tissue damage, particularly the ears Large doses can cause cancer and leukaemia

Communication using EM waves The way radio waves can be used for communication without satellites is due to charged particles in the Earth’s atmosphere. These particles reflect the radio waves back to Earth. So radio wave signals can be sent from one side of the Earth to the other. However, this doesn’t work for microwaves as they can pass through the atmosphere. So to communicate by microwaves you need to have a satellite in orbit to redirect the signal. Light Wave The way that light can be used for communication is in optical fibres. When the light travels through the optical fibre it gets reflects inside the fibre. This is called total internal reflection. This can also be achieved using infrared waves.

Advantages and disadvantages of analogue and digital signals Communication signals can either be sent as analogue or digital waves. Analogue signals are a continuous wave where as digital signals are a series of on-off pulses. Digital signals are less prone to interference than analogue signals Analogue signal Digital Signal Advantages and disadvantages of analogue and digital signals Digital signals Analogue signals Lose strength the further they travel High quality for however far the pulses travel Distort easily Easily stored Signal can be spoilt by interference Signal and interference can be separated Continuous signal Discrete signal

Sound The Doppler Effect Sound travels as longitudinal waves. It is the compression of particles, so without particles there can be no sound – so you wouldn’t hear anything in space!! The loudness and pitch of a sound depend on the characteristics of the sound wave. A high amplitude gives a loud sound. A low amplitude gives a quiet sound. A high frequency sound wave gives a high pitch and a low frequency sound gives a low pitch. The Doppler Effect Changes in the characteristics of waves can occur as a result of motion of the wave source. If the thing making the waves moves it can change the way the wave is perceived. In a zooming car the waves are compressed when approaching you to give a higher frequency and so you hear high pitch. When the car zooms away, the waves are stretched giving a low frequency…..so you hear a low pitch sound of the car Towards Stationary Away

Red Shift The Big Bang Theory Red shift is the Doppler effect on visible light that travels from distant galaxies. Red shift is evidence for an expanding universe because it is thought that the light waves have been stretched to larger wavelengths by moving galaxies, and so appear shifted to the red end of the spectrum of light. The opposite is true if a galaxy is moving closer. It is said to be blue-shifted. Most galaxies are moving away from Earth. The Big Bang Theory If the universe is expanding then if we retraced its steps back in time it would lead us back to an initial small explosion point. This explosion created space and time. Evidence for the Big Bang Theory exists in the from of Cosmic Microwave Background Radiation, which can be detected in every direction in space. This can only be explained by the big bang.

Sample Question (taken from 2011 specimen paper):

Sample Question (taken from 2011 specimen paper):

You’re ready for your P1 exam. Well Done !! You’re ready for your P1 exam. Good Luck !!