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24 Cards in this Set

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  • Back
P2 Revision Cards
If you can answer all of the questions on these cards then you know everything you need to know to ace your exam!
1. Describe the structure of an atom.
2. Explain how to charge an insulator using friction.
3. Explain what happens in terms of electrons moving.
4. Explain how a balloon can be made to stick to a wall.
1. Protons (+) and neutrons (no charge) are in the nucleus and electrons (-) are arranged in shells around the outside.
2. Rub the insulator with a cloth.
3. Outer shell electrons from the cloth move onto the insulator. The cloth is now positively charged and the insulator is negatively charged.
4. Rub the balloon on your jumper so that electrons are rubbed off of the jumper onto the balloon giving it a negative charge. When it is placed near the wall the electrons in the wall are repelled by the negative charge leaving a positive (induced) charge behind. The negative charge from the balloon and the positive charge of the wall attract.
1. Explain why you sometimes get electric shocks from metal door knobs.
2. Where does lightening come from?
3. How are electrostatic charges used in paint and insecticide sprayers?
4. What are some dangers of electrostatic charges and how can they be managed?
1. Electrons are rubbed off the carpet onto you, when you tough the metal door knob they flow from you through the metal to the floor. You have been discharged.
2. Static electricity builds up on the clouds. Lightening is the movement of these charged particles through the atmosphere.
3. It is used to make the paint or insecticide particles spread out. They are charged so that they repel each other.
4. Static charge can build up in fuel lines as planes are refueled, a bonding line connects the plane to the ground to earth it before refueling so that no sparks will be produced.
1. What is an electric current?
2. What is direct current?
3. What are the units of charge and current?
4. What is alternating current?
1. A flow of charged particles, in wires thiese are electrons.
2. Direct current is a flow of electrons in one direction like from a battery.
3. The units of charge are coulombs; the units of current are amperes.
4. Alternating current is a flow of electrons that changes direction many times a second like from a generator or the mains.
1. How is current measured?
2. How is voltage measured?
3. What is potential difference?
4. How can you change the current in a circuit?
5. What happens to current in a series circuit?
6. What happens to current in a parallel circuit?
1. With an ammeter placed in series in the circuit.
2. With a voltmeter placed in parallel around the component you want to measure.
3. The same as voltage! The amount of energy transferred to/from a component in a circuit.
4. Increase the voltage or decrease the resistance.
5. It is the same all around the circuit.
6. It splits at junctions.
1. What is resistance?
2. Describe the changes in resistance in these components: filament lamp; variable resistor; diodes; LDRs and thermistors.
1. A way of measuring how hard it is for current to flow through a circuit.
2. Filament lamps: resistance increases with heat, higher voltages cause more heating. Variable resistors have a lever or switch that allows you to change the resistance. Diodes only conduct electricity in one direction so no current flows if voltage is applied in the other direction. Resistance in light dependent resistors gets less the more light is shone on them. The resistance of thermistors gets less when they are heated.
1. What is often an unwanted energy transfer in electrical appliances?
2. Why does it happen?
3. What is power and what is the unit of power?
1. Heat.
2. As the electrons flow through the wire they collide with some of the ions in the lattice transferring energy to them.
3. Power is the energy transferred every second. It is measured in watts.
1. What are vector quantities?
2. Give 3 examples of vector quantities.
3. How can you calculate speed from a distance-time graph?
4. What is acceleration?
5. How is it calculated?
1. Quantities that have both a size and a direction.
2. Velocity, displacement; and force.
3. The gradient of the line tells you the speed.
4. The change in velocity - can be speeding up or slowing down.
5. Final velocity - start velocity / time taken
1. What does a horizontal line mean on a velocity-time graph?
2. What does a downward sloping line mean?
3. What does an upward sloping line mean?
4. How can you calculate distance from a velocity-time graph?
1. An object is travelling at a constant speed or stationary if it is at the bottom of the graph.
2. An object is slowing down.
3. An object is speeding up.
4. Work out the area beneath the line on the graph.
1. What is a force?
2. What is a free-body diagram?
3. What happens when two objects touch?
4. How are rockets propelled?
1. A push or a pull.
2. A diagram that show the forces acting on an object with arrows. The size of the arrows indicates the relative sizes of the forces.
3. There are two forces acting on them that are equal size but in opposite directions; these forces are called action and reaction forces.
4. The rocket pushing out the gases is the action force and the gases pushing back on the rocket is the reaction force that makes the rocket move.
1. What is a resultant force?
2. What happens to an object if the resultant force acting on it is zero?
3. What happens to an object if the resultant force acting on it is more than zero?
4. What factors determine the acceleration of an object?
1. The sum of all of the forces acting on an object.
2. It is either stationary or moving at a constant speed.
3. It is either speeding up or slowing down.
4. The mass of the object and the size of the force acting on it.
1. What is the difference between mass and weight?
2. How strong is gravitational field strength on Earth?
3. Would a hammer or a feather land first in a vacuum?
4. Why?
5. What about on Earth?
6. Why?
7 What is terminal velocity?
1. Mass is the quantity of matter there is in an object and weight is a measure of the pull of gravity on that object. Weight is a force and is measured in Newtons but mass is is not a force and is measured in kg.
2. 10 N/kg
3. They would land at the same time.
4. Because all objects accelerate at the same rate in a vacuum.
5. The hammer would land first.
6. Because there is less air resistance acting on it to slow it down.
7. The point at which the force of gravity and air resistance acting on an object are equal.
1. What is stopping distance?
2. What factors affect stopping distance?
3. What is momentum?
4. What happens to momentum when objects collide?
1. Thinking distance + braking distance. The distance it takes before a vehicle stops.
2. The mass of the vehicle; its speed; the drivers reaction time; the state of the vehicles brakes; the state of the road; and the amount of friction between the road and the vehicles tyres.
3. A measure of how strongly something is moving. It is a vector quantity.
4. Momentum is conserved so the sum of the momentums of the 2 objects will be the same as before the crash.
1. Name some safety features that reduce change in momentum.
2. How do they work?
1. Air bags, crumple zones, seat belts and bubble wrap.
2. They increase the amount of time over which the change in momentum occurs which decreases the size of the force acting on the object.
1. What is work?
2. What is it measured in?
3. What is power?
4. What is gravitational potential energy?
5. What is kinetic energy?
6. What happens to the total amount of energy when it is transferred from one type to another?
1. A transfer of energy.
2. Joules.
3. The rate of doing work, measured in watts.
4. Energy that is stored when an object is raised above the ground.
5. Movement energy.
6. It remains the same, called the conservation of energy.
1. What are isotopes?
2. What is ionising radiation?
3. What are the 3 types of ionising radiation?
4. Compare them.
1. Atoms that have the same number of protons but different numbers of neutrons and therefore different masses.
2. Radiation that has enough energy to cause atoms to lose electrons and become ions.
3. Alpha particles; beta particles; and gamma rays.
4. Alpha particles have 2 protons and 2 neutrons but no electrons; they have a short penetration distance (stopped by paper) but are very ionising. Beta particles are electrons emitted from unstable nuclei; thay have a longer penetrating distance (stopped by tin foil) but are less ionising. Gamma rays are a form of electromagnetic radiation; they have the longest penetrating distance (stopped by lead or thick concrete) but are the least ionising.
1. Describe the 3 types of nuclear reactions.
2. How does nuclear fission work?
3. What is the difference between nuclear fission and nuclear fusion?
1. Radioactive decay: the emission of alpha and beta particles from unstable nuclei; nuclear fission: unstable nuclei split to form 2 daughter nuclei; nuclear fusion: small nuclei are joined to form larger ones.
2. A neutron is absorbed by a uranium-235 nucleus which causes it to split into 2 smaller nuclei and release 2 neutrons which can then make other uranium-235 nuclei split in a chain reaction.
3. Nuclear fission is the splitting of nuclei and fusion is the joining of nuclei. Both release lots of energy.
1. How does a nuclear reactor work?
2. How is electricity generated in a nuclear power plant?
1. Uranium fuel is contained in rods in the reactor core. A fission chain reaction is started by the release of a neutron from one of the uranium nuclei. The chain reaction is controlled by the absorption of excess neutrons by elements within the control rods. If the rate of fission needs to be increased the control rods are removed from the core. If it needs to be slowed down or stopped they are lowered into the core.
3. The thermal energy from nuclear fission is used to heat water into steam to turn a turbine which turns a generator.
1. What is one problem with nuclear power?
2. What is the problem with ionising radiation?
3. How have ideas about radiation changed over time?
4. What precautions are necessary when working with radioactive sources?
1. It generates radioactive waste which is difficult to store and dispose of.
2. It can cause mutations to DNA which can lead to cancer.
3. When it was first discovered people thought it was safe and it was used in a variety of products but now we know that it is dangerous and needs to be treated with caution.
4. Handle sources with tongs; don't point them at people; and keep them in lead lined containers.
1. What is nuclear fusion?
2. Explain why it doesn't happen at low temperatures and pressures.
3. Why is it impractical to make a fusion power station?
1. The creation of larger nuclei from smaller ones as happens in stars.
2. At low temperatures and pressures there is not enough energy to overcome the electrostatic repulsion between nuclei.
3. At the moment any reactors we have made have used more energy creating the high temperatures and pressures needed to overcome this electrostatic repulsion than they have created by nuclear fusion.
1. What are the 3 types of radioactive waste?
2. How are they transported, stored and disposed of?
1. High level waste (HLW) produces large amounts of ionising radiation for 50 years; intermediate level waste (ILW) is less radioactive but remains so for thousands of years; low level waste (LLW) only slightly radioactive.
2. HLW: transported in thick concrete and steel containers and then sealed in glass. ILW: stored in concrete and steel containers. Neither have been disposed of yet. LLW: compacted and buried in special land fill sites.
1. Compare the 3 possible methods of disposing of nuclear waste.
2. What are the advantages and disadvantages of nuclear power?
1. Firing into space: vehicle could fall back to Earth and spread radioactive material; dumping in barrels in sea: barrels could corrode and release waste into the sea; storage underground: site would need to be geologically stable.
2. Advantages: doesn't produce carbon dioxide.
Disadvantages: nuclear waste has to be stored for tens of thousands of years and there is a risk of an accident such as happened in Chernobyl which spreads radioactive material over a wide area.
1. What is the half-life of a radioactive material?
2. How is radioactive decay measured?
3. How is radioactivity measured?
4. What is background radiation and where does it come from?
1. The time taken for half of the unstable nuclei in a sample to decay.
2. The number of decays per second, the unit is the becquerel (Bq).
3. With a Geiger-Muller tube.
4. Ionising radiation that is around us all the time. It comes from radon gas, the ground, space, food and drink and medical instruments.
1. What are some uses of radiation?
1. Irradiating food to kill bacteria on it; sterilising medical instruments; diagnosis of cancer using a tracer which can be detected by a gamma camera; treatment of cancer by radiotherapy - using gamma rays to kill cancer cells; smoke alarms - using a source of alpha particles which are absorbed by smoke particles which decreases the current flowing in the circuit in the smoke alarm and sets off the alarm; checking the thickness of paper; and as tracers to detect leaks in pipes.