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24 Cards in this Set
- Front
- Back
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How is static electricty build up? |
When two insulating materials rub of each other through friction, Electrons are tranferred |
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How is a charge gained? |
Negative charge= when the object gains electron Positive charge= when the object loses electrons |
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Shocks and sparks caused by static electricity |
1.Friction causes electron transfer 2. When you touch a conducting object the charge flows 3. The movement of charge can give you a shock |
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Inducing a charge |
Example: Balloon and wall 1. Ballon can gain a charge by rubbing with clothes 2.When you hold it against a wall it will stick 3. The negative charges on the balloon repel the negative charges on the wall 4. This leaves the positive charge on the surface which attracts the balloon |
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Lightining- static electricity |
1.Rain drops and ice clouds collide with each other which knocks of electrons 2. This leaves the top of the cloud positivly charged and the bottom negativly charged 3. A huge spark is produced when the charge suddenly flows to the ground |
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Paint sprayers |
1. The spray gun is charged, the droplets all have the same charge 2. Like charges repel so this makes an even coat 3. The object being charged is given the opposite the charge 4. Opposite charges attract so less paint is wasted |
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Earthing |
1.Sparks can be prevented by earthing 2. It is connected to the ground using a conductor ( metal wire) 3. Earthing allows the charge to flow to the ground 4. This can avoid sparks |
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Current, Voltage and resistance |
Current= the rate of flow of charge Voltage= the driving force which pushes the current Resistance= Slows the current down |
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Devices and Resistance |
Fixed resistor= current is proportional to voltage Filament lamp= as filament gets hotter, resistance increases Diode= only goes in one direction LDR= as light intensity increases, resistance decreases Thermistor= as temperature increases, resistance decreases |
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Speed and Velocity |
Speed= Scalar quantity, doesn't involve direction Velocity= has magnitude and direction (vector quantity) |
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Acceleration |
Vector quantity How quickly the velocity is changing |
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Distance-time Graph |
Gradient=speed Flat section=stopped Downhill= going back to start Curves= acceleration |
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Velocity-time Graphs |
Gradient- acceleration Flat sections= constant speed Curve= changing acceleration |
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Weight and mass |
Weight= measured in newtons, caused by the pull of gravity Mass= kg |
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Terminal velocity |
1.At first it has much more weight than air resistance 2. As it speeds up air resistance increases 3. Eventually the air resistance is equal to the weight, when they are balanced they wont accelerate any more= terminal velocity |
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Zero resultant force |
The forces are balanced The objects remainn stationary Travel at constant speed If it is not zero it will accelerate |
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Stoping distance= braking distance + thinking distance |
Thinking distance= Reaction time , how fast you are going Stopping distance=speed, mass, brakes and grip |
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Momentum |
A vector quantity In collisions momentum is conserved The longer the change in momentum the smaller the force |
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Car safety |
Crumple zones= Increases time taken to stop and reduces force Seat belts= stretch to increase the time air bags= make passengers slow down Bubble wrap is the same to the crumple zone |
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Falling objects |
Turn GPE to KE some will also be transferred as heat due to air resistance The total amount of energy stays the same |
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Fission |
Happens when a neutrons is aborbed by a uranium235 nucleus which then splits into two daughter nuclei and 3 neutrons and releases a lot of energy This can make a chain reaction |
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Fusion |
When two small nuclei fuse to form a larger one and release a lot of energy Doesn't leave a lot of radioactive waste There is also a lot of hydrogen to use |
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Bckground radiation |
Low levels of radiation that is around all the time |
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Uses of radioactivity |
Alpha-Fire alarms Beta - controlling thickness Gamma- tracers, radiotherapy, sterilisation |
