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45 Cards in this Set
- Front
- Back
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What causes static? |
2 insulating materials are rubbed together and charged by friction.The friction removes electrons from one object and gives it to the other giving them opposite charges. When the charge is released it cases a shock. |
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What happens if you put a charged object near a neutral one like a wall? |
If the object was positive, the positive charge on the wall would be repelled and the negative charge would be attracted. |
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How is lightning caused by a build-up of static charge? |
The rain drops and ice bump together in storm clouds giving the top of the cloud positively charged and the bottom negative. |
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How do elecrostaic paint sprayers work? |
The paint is given a charge so the paint particles repel and give a fine coat. The object to be painted is then given the opposite charge s the paint particles are attracted to the object. This minimises waste. |
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What is earthing? |
Charged objects can be earthed to removethe charge safely. A wire touches the ground and charge flows down it if the object is negatively charged and up it if it's positive. |
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What is current? |
The rate of flow of charge round a circuit. Amps |
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What is voltage? |
The push on electrons round a circuit. Volts |
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What is resistance? |
Anything in the circuit which slows the flow of elecrons down. Ohms |
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Where is the voltmeter placed? |
In parallel around the component it is measuring. |
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What does an LDR do? |
When there is more light, the LDR reduces resistance allowing more current to flow. When it's dark, the LDR increases resistance, reducing current flow. |
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What does a thermistor do? |
When it's hot, resistance decreases allowing more current to flow. When it's cold, resistance increases allowing less current to flow. |
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Why do resistors heat up? |
This s because, electrons collide with the ions in the metal lattice of the resistor.This causes friction which transfers kinetic energy to thermal energy. |
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What is power? |
The rate at which an appliance transfers energy. |
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What is a scalar quantity? |
A quantity measured with numbers and units. For example, speed and mass. |
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What is a vector quantity? |
A quantity measured with numbers, units and a direction. It's a force. For example, velocity and weight. |
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What does it mean if fores on an object are balanced? |
This means that the object is either stationary or at a constant speed. |
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What is resultant force? |
All forces added together to find the total overall force. |
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What affects thinking distance? |
Reaction time How fast you're going |
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What affects braking distance? |
How fast you're going Mass of the vehicle How good your brakes are How good the grip is |
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What is work done? |
The energy tranferred when a force moves an object. |
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What is power? |
The rate of work done. |
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What is alpha decay? |
Two protons and two neutrons (a helium nucleus) released from an unstable nucleus. It can only pass through paper and is highly ionising. |
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What is beta decay? |
This is an electron emitted when an unstable nucleus turns a neutron into a proton and releases an electron. It can pass through thin aluminium and is less ionising than alpha. |
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What are gamma waves? |
Waves emitted from an unstable nucleus. They can pass through thick lead and are not very ionising. |
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What is induction? |
Where a charged object forces charges in an uncharged object to move. |
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How do insecticide sprayers work? |
When insecticideis released from planes, it may blow away or distribute unevenly. To combat this, the insecticide is given a charge so it gives an even coat and is attracted to Earth. |
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Current is... |
the rate of flow of charge |
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What is current in metals? |
A flow of electrons |
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How is current conserved? |
Current is conserved at a junction in a parallel circuit because the amount of current in equals the amount of current flowing out. |
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P.D. is |
energy transferred per unit charge passed |
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1 volt = |
1 joule per coulomb |
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When two bodies act on each other... |
the forces they exert on each other are equal but in opposite directions. These are action and reaction forces |
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In a vacuum... |
All objects have the same acceleration |
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What is the correlation between air resistance and speed? |
As speed increases, so does air resistance. Air resistance increases until it's equal to weight. at this point, the object is at terminal velocity. |
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A watt = |
A joule per second |
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Kinetic energy when a car is moving= |
work done when stopping |
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Unit of radioactivity |
Becquerel |
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Advantages of nuclear power |
Cost is similar to coal Doesn't produce smoke/CO2 Little fuel gives lots of energy |
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Disadvantages of nuclear power |
Non-renewable Risk to life Power station expensive Need safe disposal |
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How is low level waste disposed of? |
Metal drums, covered in concrete in clay lined landfill sites |
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How is medium level waste disposed of?
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Mixed with concrete in steel drums and put into stores |
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How is high level waste disposed of?
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Stored underwater in casks, then in a well ventilated area underground |
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Sources of background radiation |
Cosmic rays,radon gas,food,rocks,hospitals,nuclear bombs and power plants. |
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What do moderators do in fission? |
They slow down neutrons to allow them to be captured by uranium so that the chain reaction can continue. If they didn't the neutrons would go to fast to be captured and the chain reaction would stop. |
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How is lightning caused by static? |
Rain drops and ice bump together in clouds, leaving the top positively charged and bottom negative.This creates a huge voltage and a big spark. |
