1
Q
What does LED stand for?
A
Light-emitting diode
2
Q
When do LEDs emit light?
A
When a current flows through them in a forward direction
3
Q
What are they used for?
A
The numbers in digital clocks, in traffic lights and in remote controls
4
Q
How are they different from a light bulb?
A
They don’t have a filament that can burn out
CGP GCSE Physics
flashcards
Decks in class (237)
# Cards
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Speed and Velocity are Both How Fast You’re Going5
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Acceleration is How Quickly Velocity is Changing6
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Distance-Time Graphs Tell You How Far Something has Travelled8
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Velocity-Time Graphs can have a Positive or Negative Gradient7
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Gravity is the Force of Attraction Between All Masses7
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Weight and Mass are Not the Same10
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The Very Important Formula Relating Mass, Weight and Gravity6
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There are Loads of Different Types of Force8
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You Can Draw the Forces Acting on a Body4
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Friction is Always There to Slow Things Down13
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You can Investigate the Motion of a Toy Car on a Ramp7
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You Could Play Around with the Experimental Set-up7
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First Law - Balanced Forces Means No Change in Velocity4
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Second Law - A Resultant Force Means Acceleration5
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Resultant Force = Mass x Acceleration5
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Resultant Force is Real Important - Especially for ‘F = ma’5
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The Third Law - Reaction Forces7
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Vectors Have Size and Direction - Scalar Quantities Only Have Size6
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To Work Out Resultant Force You Need to Combine Vectors1
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Moving Objects Can Reach a Terminal Velocity5
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The Terminal Velocity of Falling Objects Depends on Their Shape and Area11
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Hooke’s Law Says that Extension is Proportional to Force7
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You Can Investigate Hooke’s Law with a Spring9
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Hooke’s Law Stops Working when the Force is Great Enough8
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A Material Can Return to its Original Shape After an Elastic Deformation2
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Many Factors Affect Your Total Stopping Distance3
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Thinking Distance4
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Braking Distance9
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Momentum = Mass x Velocity3
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Momentum Before = Momentum After3
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Forces Cause Changes in Momentum11
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A Moment is the Turning Effect of a Force6
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The Centre of Gravity Hangs Directly Below the Point of Suspensión8
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A Question of Balance - Are the Moments Equal?2
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Forces are Not Always Equal Across All Supports3
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And if the Moments are Not Equal...2
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The Properties of a Circuit13
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The Standard Test Circuit4
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Five Important Points4
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Mains Supply is a.c, Battery Supply is d.c6
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There’s a Formula Linking V and I5
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Four Hideously Important Current-Voltage Graphs5
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Light-Emitting Diodes are Really Useful4
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Some Components Can Change Resistance9
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Series Circuits - All or Nothing10
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Parallel Circuits - Everything is Independent13
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Charge Through a Circuit Depends on Current and Time3
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When a Charge Drops Through a Voltage it Transfers Energy10
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Appliances must be Earthed or Insulated11
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Earthing and Fuses Prevent Fires and Shocks4
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Circuit Breakers Have Some Advantages Over Fuses10
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Resistors Get Hot When an Electric Current Passes Through Them7
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Electrical Power and Fuse Ratings9
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Electrical Appliances Transfer Energy Electrically2
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Like Charges Repel, Opposite Charges Attract3
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Conductors Conduct Charges - Insulators Don’t4
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A Static Charge Cannot Move13
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As Charge Builds Up, So Does the Voltage4
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Investigating Static Electricity4
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Gold-Leaf Electroscope7
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Suspending a Charged Rod3
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Van de Graaf Generators Make Your Hair Stand on End4
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Inkjet Printer5
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Photocopier5
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Clothing Crackles2
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Lightning2
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The Fuel-Filling Nightmare4
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All Waves Have Wavelength, Frequency, Amplitude and Speed6
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Wave Speed = Frequency x Wavelength2
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Waves Can Be Transverse or Longitudinal8
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All Waves Transfer Energy and Information Without a Transferring Matter6
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Two or More Waves Moving Together Have Wavefronts4
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The Doppler Effect Makes Waves Longer or Shorter6
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There are Seven Types of Electromagnetic (EM) Waves7
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Radio Waves are Used Mainly for Communications6
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Microwaves are Used for Satellite Communication and Heating Food9
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Infrared Radiation is a Used for Heating and to Monitor Temperature7
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Light Signals Can Travel Through Optical Fibres5
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Visible Light is Also Useful for Photography4
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Ultraviolet is Used in Fluorescent Lamps6
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X-Rays Let Us See Inside Things6
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Gamma Radiation Can be Very Useful For Sterilising Medical Equipment2
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Gamma Radiation Can be Very Useful For Sterilising Food3
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Some EM Radiation Can be Harmful to People3
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Higher Frequency EM Radiation is Usually More Dangerous4
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Reflection of Light Lets Us See Things13
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Waves Can be Refracted7
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Draw A Ray Diagram for a Refracted Wave9
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Rays Passing Through a Glass Block are Refracted Twice10
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Triangular Prisms Disperse White Light3
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Every Transparent Material Has a Refractive Index8
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Find the Refractive Index of Glass a Using a Glass Block6
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Use Semicircular Blocks to Show Total Internal Reflection13
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You Can Use Snell’s Law to find Critical Angles4
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Optical Fibres and Prisms Use Total Internal Reflection7
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Sound Travels as a Wave11
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An Oscilloscope Can Display Sound Waves6
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Loudness Increases with Amplitude3
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The Higher the Frequency, the Higher the Pitch8
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Find the Period of a Wave on an Oscilloscope to get its Frequency4
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You Can Use an Oscilloscope to Measure the Speed of Sound7
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Energy is Transferred Between Energy Stores14
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There is a Principle of Conservation of Energy2
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Most Energy Transfers Involve Some Losses, Often by Heating4
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You can Calculate the Efficiency of an Energy Transfer2
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How to Use the a Formula - Nothing to It3
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We Generally Can’t do Anything Useful with Wasted Energy3
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A Ball Rolling Up a Slope3
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A Bat Hitting a Ball3
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An Electric Kettle Boiling Water2
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A Battery-Powered Toy Car3
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A Bunsen Burner and Beaker3
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The Thickness of the Arrow Represents the Amount of Energy5
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Energy Transfer by Heating can Happen in Three Different Ways6
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Thermal Radiation Involves Emission of Electromagnetic Waves6
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Conduction - Occurs Mainly in Solids4
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You Can do an Experiment to Demonstrate Conduction5
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Convection of Heat - Liquids and Gases Only2
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The Immersion Heater Example8
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You Can See Convection Currents Using Coloured Crystals4
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You Can Reduce the Rate of Energy Transfer8
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You Can Investigate Emission of Thermal Radiation With a Leslie Cube12
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‘Work Done’ is Just ‘Energy Transferred’5
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And Another Formula to Learn2
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Power is the ‘Rate of Doing Work’ - I.e How Much per Second5
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Movement Means a Energy in an Object’s Kinetic Energy Store6
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Raised Objects Store a Energy in Gravitational Potential Energy Stores6
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Falling Objects Also Transfer Energy3
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Non-Renewable Energy Resources Will Run Out One Day6
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Most Power Stations Use Steam to Drive a Turbine5
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Advantages of Fossil Fuels3
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Disadvantages of Fossil Fuels3
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Nuclear Reactors are Just Fancy Boilers7
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Wind Farms - Lots of Wind Turbines4
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Geothermal Power - Heat from Underground8
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You Can Capture the Sun’s Energy Using Solar Cells11
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Solar Water Heating Panels4
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Cooking with Solar Power3
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Wave Power - Lots of Little Wave Converters8
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Tidal Barrages Generate Energy When the Tide Goes In and Out8
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Hydroelectricity - Catching Rainwater11
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Pumped Storage Gives Extra Supply Just When it’s Needed6
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Density is Mass per Unit Volume7
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You Can Find the Density of an Object from its Mass and Volume3
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Pressure is Force per Unit Area8
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Pressure Differences in Liquids and Gases Depends on Density4
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Kinetic Theory Can Explain the Three States of Matter18
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Evaporation is a Special Example of Changing States9
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You Can Obtain a Temperature-Time Graph for Water6
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Absolute Zero is as Cold as Stuff Can Get - 0 Kelvins7
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Energy in Particles’ Kinetic Energy Stores is Proportional to Temperature9
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Particle Theory Says Colliding Gas Particles Create Pressure8
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At Constant Temperature ‘pV = Constant’2
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At Constant Volume ‘p/T = Constant’2
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Specific Heat Capacity Relates Temperature and Energy11
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You can Find the Specific Heat Capacity of Water12
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Magnets Produce Magnetic Fields5
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Magnetic Field Patterns can be Seen Using Compasses3
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Magnetism can be Induced8
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A Current-Carrying Wire Creates a Magnetic Field3
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The Magnetic Field Around a Straight Wire2
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The Magnetic Field Around a Flat Circular Coil2
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The Magnetic Field Around a Solenoid4
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Magnetic Materials can be ‘Soft’ or ‘Hard’7
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A Current in a Magnetic Field Experiences a Force14
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Fleming’s Left-Hand Rule Tells You Which Way the Force Acts3
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4 Factors which Speed up a Simple D.C Electric Motor9
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Loudspeakers Work Because of the Motor Effect4
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Electromagnetic Induction1
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The Dynamo Effect - Move the Wire or the Magnet10
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A.C Generators - Just Turn the Coil and There’s a Current9
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Transformers Change the Voltage - but Only Alternating Voltages8
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The Transformer Equation - Use it Either Way Up5
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Transformers are Nearly 100% Efficient So ‘Power in = Power Out’2
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Transformers Make Transmitting Mains Electricity More Efficient5
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At the Centre of Every Atom is a Nucleus8
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Isotopes are Atoms with Different Numbers of Neutrons6
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Radioactive Decay is a Random Process6
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Background Radiation is Everywhere All the Time2
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Nuclear Radiation Causes Ionisation4
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Alpha Particles are Helium Nuclei7
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Beta Particles are Electrons8
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Gamma Rays are Very a Short Wavelength EM Waves9
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You Can Identify the Type by its Penetrating Power3
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You can Investigate the Penetration of a Radiation14
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Balancing Nuclear Equations4
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The Radioactivity of a Sample Always a Decreases Over Time6
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Measuring the Half-Life of a Sample Using a Graph4
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Medical Tracers Use Beta or Gamma Radiation8
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Radiation is Also Used to Treat Cancer4
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Food and Equipment can be Sterilised Using Gamma Rays4
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Radiation is Used in Industry for Tracers and Thickness Gauges10
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Ionising Radiation Can Damage Cells and Tissues8
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Exposure to Radiation is called Irradiation3
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Contamination is Radioactive Particles Getting onto Objects4
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Radioactive Waste is Difficult to Dispose of Safely5
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Nuclear Power Stations use Nuclear Fission Chain Reactions1
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Nuclear Reactors Have to Work-Safely10
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Nuclear Fusion - Joining Small Nuclei7
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We are Part of the Milky Way Galaxy9
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Our Solar System has One Star - The Sun7
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Gravity Provides the Force That Creates Orbits9
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The Force due to Gravity Depends on Mass and Distance9
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There are Different Types of Orbit5
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You can Calculate Orbital Speeds3
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Stars can be Classified by their Colours13
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You can Compare Brightness using Absolute Magnitude9
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You can See Different Types of Star on the Hertzsprung-Russell Diagara,6
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Waves are Affected by the Motion of the Source5
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Light from Galaxies is Red-shifted6
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Calculating Red-shift1
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Red-shift Suggests the Universe is Expanding5
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There’s Microwave Radiation from All Directions4
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This Evidenced Suggests the Universe Started with a Bang5
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Microwaves4
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Infrared4
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Ultraviolet4
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Gamma5
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The Transformer Equation - Use it Either Way Up5
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Stars 1.1
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Stars 2.5
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Stars 3.4
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Stars 5.2
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Stars 6.3
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Stars 7.3
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Stars 8.6
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Stars 4.5
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Burgess mini test37
