Physics Topic 1-7 (PAPER 1)

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What is a system?
An object or a group of objects
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What happens to the energy in a system if the system changes?
The way the energy is stored changes
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What is a closed system?
One where neither matter nor energy leave. The net change of the total energy of a closed system is always zero.
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What are the eight types of energy store?
Thermal, Kinetic, Gravitational potential, Elastic potential, Chemical, Mechanical, Electrostatic, Nuclear
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In what five ways can energy be transferred?
Mechanically (a force doing work), electrically (work done by moving charges) by heating or by radiation (light or sound)
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Describe the energy transfers that occur when a person throws a ball upwards
The force exerted by the person to throw the ball upwards does work. It causes energy to be transferred mechanically from the chemical energy store of the person's arm to the kinetic energy store of the ball and the arm.
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Describe the energy transfers that occur when a ball is dropped from a great height.
The gravitational force of the earth does work on the ball, causing it to accelerate because energy is transferred away from the ball's gravitational energy store to its kinetic energy store.
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Describe the energy transfers that occur when a car slows down
The friction between the wheels and the breaks does work, which causes energy to be transferred from the wheel's kinetic energy stores to the thermal energy store of the brakes and the surroundings.
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When asked to describe the energy transfers when a system changes, what three things should you state?
1. The energy stores the energy is being transferred from and too 2. How the energy is transferred - and if it is by a force doing work: 3. What force is doing work (transferring the energy)
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What equation can you use to calculate the kinetic energy (J) of a moving object? Include units
0.5 x mass (kg) x speed(m/s)^2
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What equation can you use to calculate the amount of elastic potential energy (J) in a stretched spring? Include units. To use this equation what must me assume?
0.5 x spring constant N/m x extension(m) ^2. We must assume the limit of proportionality has not been exceeded.
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What equation can you use to calculate the amount of gravitational potential energy in an object raised above ground level? Include units
Change in height (m) x Gravitational field strength N/kg (kg) x Mass (kg)
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What is the gravitational field strength on earth?
9.8 N/kg
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What equation can we use to calculate the amount of thermal energy stored or released from a system as it changes temperature? Include units
Mass (kg) x specific heat capacity x temperature change (Degrees Celsius)
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What is the specific heat capacity of an object?
The amount of energy required to raise the temperature of 1 kg of the substance by 1 Degree Celsius
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What can we deduct about materials that need to gain a lot of energy to heat up (have a high specific heat capacity)?
They will transfer a lot of energy when they cool down again - so they can 'store' a lot of energy
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What is power?
The rate at which work is done or energy is tranferred
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Give the two formulas for power involving work done and energy transferred
Power (Watts) = Energy transferred (joules) / time (seconds) and Power (Watts) = work done (joules) / time (seconds)
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What is the principle of the conservation of energy?
Energy can be tranferred useful, stored or dissipated, but can never be created or destroyed
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What is 'wasted' energy?
Energy that has been dissipated (not transferred usefully)
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How can we reduce unwanted energy transfers?
By lubrication, streamlining or by insulation
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How does lubrication help reduce unwanted energy transfers? Give one example of lubrication to reduce unwanted energy transfers.
Reduces frictional forces between moving parts and therefore the amount of energy lost as heat
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Name two methods of insulation used to prevent conduction
1. Double glazed windows with an air gap 2. Cavity wall insulation
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What can we say about a material with a high thermal conductivity?
The faster the rate of energy transfer by conduction across the material (transfers energy between its particles quickly).
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How is the rate of cooling of a building affected by the thickness and thermal conductivity of its walls?
The thicker the walls and the lower their thermal conductivity, the slower the rate of energy transfer through the walls will be, therefore the slower the rate of cooling of the building will be.
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Give the two equations for efficiency and state the units
Efficiency (%) = useful energy output(J) /total energy input (J) and Efficiency (%) = useful power output (W) /total power input (W)
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What is a renewable energy resource?
One that is being replenished as quickly as it is used up; therefore it will never run out
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Name all the energy resources available on earth
Nuclear, biofuel, fossil fuels (coal, oil, natural gas), geothermal, solar, wind, the tides, hydro-electric, water waves
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What are energy resources used for?
Heating, transport, electricity generation
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Which energy resources are renewable?
Geothermal, water wave, biofuel, hydro-electric, wind, the tides, solar
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Which energy resources are not renewable?
Nuclear and fossil fuels (coal, oil and gas)
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How are non-renewable energy resources used in transport?
Petrol and diesel are fuels derived from oil. Coal is used in old-fashioned steam trains to produce stream.
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How are renewable energy resources used in transport?
Some vehicles run on pure bio-fuel or a mix of bio-fuel and other fuels
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How are non-renewable energy resources used for heating?
Natural gas is used to heat the waters in radiators. Coal can be burnt in fireplaces. Electric heaters use electricity generated from non-renewable sources.
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How are non-renewable energy resources used for heating?
Solar panels can be used to heat the water inside radiators. Geothermal heat pumps can be used to heat buildings. Burning bio-fuel (or using electricity generated from other renewable resources) can be used in electric heaters etc.
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Why are renewable energy resources less reliable than renewable energy resources?
They are weather-dependant and cannot increase energy output on demand.
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Give an advantage and a disadvantage of wind turbines
Advantage: no permanent damage to the landscape (when removed) // Disadvantage: They are very noisy and spoil the view (disturbs residents)
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Give an advantage and a disadvantage of solar panels
Advantage: good for remote areas // Disadvantage: initial costs are high
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Give an advantage and a disadvantage of geothermal power
Advantage: Very reliable // Disadvantage: Not many suitable locations
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Give an advantage and a disadvantage of hydro-electric power
Advantage: Can provide immediate response to increase in demand for energy // Disadvantage: Have to flood a valley - large CO2 output and animals lose their habitat
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Give an advantage and a disadvantage of wave power
Advantage: No pollution and minimal running cost // Disadvantage: hazard to boats and disturbs marine life
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Give an advantage and a disadvantage of tidal barrages
Advantage: Tides are consistent day to day and can produce significant amounts of energy // Disadvantage: Prevents free access by boats and neap and spring tides vary
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What are the general advantages and general disadvantages to renewable resources?
ADVANTAGES: No fuel cost and minimal running cost (but NOT for geothermal) Also little to no damage to the environment DISADVANTAGES: Unreliable/weathers dependant and can't increase energy output on demand
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What are the advantages and disadvantages to bio-fuel?
Advantages: They are supposedly 'carbon neutral' and they are reliable as crops for bio-fuel can be grown quickly and all year round // Disadvantages: People worry it is taking up food-crop space and also contributes to deforestation
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What are the advantages and disadvantages to non-renewables?
Advanatges: fuel extraction costs are low, they are cost-effective, reliable and can increase energy output on demand // Disadvantages: Contribute to global warming, release sulphur dioxide, oil spillages, open-casting mines and nuclear waste
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What is this symbol for?
A fuse
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What is this symbol for?
A resistor
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What is this symbol for?
A variable resistor
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What is this symbol for?
A battery
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What is this symbol for?
A cell
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What is this symbol for?
An ammeter
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What is this symbol for?
A voltmeter
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What is this symbol for?
A diode
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What is this symbol for?
A LED (Light Emitting Diode)
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What is this symbol for?
A LDR (Light Dependent Resistor)
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What is this symbol for?
A thermistor
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What is conduction?
Conduction is when vibrating particles transfer energy to neighbouring particles, by collisions which cause energy to be transferred between their kinetic energy stores.
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What is thermal conductivity?
A measure of how quickly energy is transferred across a material by conduction
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What is convection?
Convection is where energetic particles move from hotter to cooler regions in a liquid or gas.
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What is a convection current?
Particles are heated, gain energy and move to cooler regions, where they lose energy and fall back to hotter regions.
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Which is has a higher density in a convection current ; hotter regions or colder regions?
Colder regions
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How does streamlining reduce unwanted energy tranfers?
Less work needs to be done to overcome air resistance (therefore less energy is lost doing this)
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How does insulation reduce unwanted energy transfers?
Preventing energy loss through heating by slowing the rate of conduction or convection
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Name two methods of insulation that prevent convection
1. Loft insulation 2. Draft excludes.
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Why does leaving an air gap in cavity walls or double-glazed windows help reduce heat loss through conduction?
Air has a lower thermal conductivity than glass and the material most walls are made from.
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True or false: no device is ever 100% efficient
True (except when its an electric heater - and even that is by accident)
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What is current?
Current is rate of flow of charge
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What is charge flow?
Flow of electrons
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What is the equation that links current, time and charge flow? Include units
Current (A) = Charge flow (C) / Time (s)
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What is the equation that links potential difference, current and resistance?
Potential Difference (V) = Current (A) x Resistance (Ω)
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What is an ohmic conductor?
Ohmic conductors are wires or resistors
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What happens to the resistance in an ohmic conductor when current increases?
If the ohmic is at a constant temperature then the current flowing through it, is directly proportional to the potential difference across it (resistant is constant). So if current increases, so does voltage (but not resistance)
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For a given potential difference, what happens to the current flowing through a component if the resistant increases
When potential difference is constant, if resistance increases, current decreases (according to the formula I = V/R resistance is inversely proportional to current)
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What is Ohms Law?
The current flowing through a resistor at a constant temperature is directly proportional to the potential difference across it
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Explain Ohms Law
Resistance increases with temperature, so in resistors where the temperature is constant, current will be directly proportional to potential difference I = V/R
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What happens to the resistance in an filament light bulb conductor when current increases?
The bulb in a filament light is designed to heat up when current flows through it (some energy is transferred to its thermal energy store). Resistance increases with temperature so as current increases, the lamp heats up the resistance increases
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What happens when current flows through a diode?
In one direction, it will happily let current through but in the other direction, it will have very high resistance.
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What happens when current flows through a variable resistor?
Resistance increases with current
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Draw the I-V characteristic for an ohmic conductor
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Draw the I-V characteristic for a filament bulb
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Draw the I-V characteristic for a diode
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What are sensing circuits?
Circuits that depend on outside conditions to change things such as resistance, potential difference or current
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What is an LDR? How does it work?
An LDR is a light dependent resistor, when light is low resistance increases and when there is bright light, resistance decreases.
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What is a thermistor? How does it work?
A thermistor is a temperature dependent resistor, when temperature is high resistance is low, but when temperature is low, resistance is high.
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What is the difference in potential difference from one component to the next for series circuits
Potential difference is shared between various components. So the potential difference adds up to the voltage of the battery/cell V(battery) = V1 + V2 + V3
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What is the difference in current from one component to the next for series circuits
None, current is the same everywhere in a circuit, because the same current flows through each component I1 = I2 = I3
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What happens to the total resistance when adding a resistor in series. Why?
Total resistance goes up. Potential difference for each resistor is lower (shared) (though overall is the same). This means current across each is lower - so total current is also lower. Low current and low voltage means increased resistance.
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In a series current, what can we say about a component with a big resistance?
It has a big share of potential difference
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What happens to the total potential difference of a series circuit if another cell is added?
The voltage of the cell is added to the voltage of battery/cell already there - total voltage increases
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What is the difference in potential difference from one component to the next in parallel circuits
Each component gets the full voltage of the cell/batery so V(battery) = V1 = V2
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What is the difference in current from one component to the next in parallel circuits
When current meets a junction, it has to split, so current is shared between branches; I(total) = I1 + I2 + I3
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If two identical bulbs are connected in parallel and the total current is 6A what is the current flowing through each bulb?
3A, because they are identical, current is shared equally.
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What happens to the total resistance when adding a resistor in parallel.
If you add a resistor in parallel then the total resistance will be less than the resistor with the least resistance.
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What type of current is the mains supply? What is meant by this?
A.C (alternating current): current is constantly changing direction, this is produced by an alternating voltage
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What is alternating voltage?
When the negative and positive 'ends' keep switching
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What is the voltage of a mains supply ac (for a household)?
230 V
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What type of current do batteries and cells use? What is meant by this?
Direct current (DC) It is always flowing in the same direction, caused by a direct voltage
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What are wires exist in a cable?
Earth wire, live wire, neutral wire
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What is the structure of wires in a cable?
Copper core and flexible plastic coating with differing colours
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What is the neutral wire? What colour is it?
Blue. Carries current away - current flows in through the live wire out through this wire. It is 0V.
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What is the live wire? What colour is it?
Brown. It is the wire that provides the alternating voltage (230V) from the mains. Current flows in through the live wire.
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What is the earth wire? What colour is it?
Green and yellow. Stops the appliance casing from becoming live; it only carries current when there is a fault. It is at 0V.
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How does the earth wire prevent the casing from becoming live?
If the live wire touches the earth wire, a large current passes between them (becuase of the huge difference in voltage) this should blow the fuse and break the circuit.
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Why does touching the live wire give you an electric shock?
Your body is at 0V. If you touch a live wire, a large potential difference is produced across you and a current flows through you.
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True or fasle; you can still get an electric shock from touching the live wire of an appliance when it is switched off
True. There is still voltage in the live wire.
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Why does a current always flow across a link between earth and the live wire?
The path is low resistance and the difference in voltage is large.
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What is the power rating of an appliance?
The maximum amount of energy transferred per second
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If an appliance has a low power rating what doe this mean?
A low amount of energy is transferred per second
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True or flase; an appliance with a high power rating will be less expensive to run than one with a low one
False, higher power ratings mean more energy is transferred between stores per second so more electricity is required, so they are more expensive.
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True or false; a powerful appliance can be less efficient than a less powerful one
True, power does NOT equal efficiency; they can be transferring a lot of energy in a not useful way.
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What equation links energy, charge flow and potential difference? Include units
Energy (J) = charge flow (c) x potential difference (V)
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How does a moving charge transfer energy?
It does work against the resistance of the circuit
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Why is energy supplied to the charge a the power source of a circuit?
To 'raise' it through a potential (when a charge goes through a change in potential difference then energy is transferred)
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How does a charge 'give-up' its energy in a circuit?
When it 'falls' through a potential drop in components, the charge is given up to the component.
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What does a battery with a bigger potential difference transfer more energy?
It will supply more energy for each coloumn of charge that flows through it because the charge is 'raised up higher' at the start
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What is the equation that links power, potential difference and current? Include units
Power (W) = Potential difference (V) x Current (A)
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What equation gives you power if you know current and resistance but not potential difference?
Power (W) = (Current x resistance = potential difference) x Current (A) -> Power (W) = Current^2 (A) x Resistance (ohms)
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How is electricity transferred from a power station to consumers?
Power station -> Step-up transformer -> Cables -> Step-down transformer -> Consumer
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How is electricity distributed across the UK?
Via the National Grid
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When are usual demand increases in (a) the day (b) the year ?
(a) When people come home from school or work/ get up in the morning (b) When it gets colder and darker early in the day
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What event might cause a sudden peak in demand for electricity?
Sporting final/popular TV event
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Why do power stations run well below their maximum power output?
So there's spare capacity to cope with high demand (i.e. unexpected shut down of another station)
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Apart from running power stations below their maximum power output, what does the government do to ensure consumers are kept supplied with energy?
Smaller power stations kept on standby just incase
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The national grid transmits a huge amount of power, which requires either high current or high voltage. Why does the national grid use high voltage NOT high current?
A high current means more energy is transferred to the thermal energy store of the surroundings. Its more economical (cheaper) and efficiet to use a high voltage (this also decreases current)
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What volatge is used in the national grid?
400 000V
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Why must the voltage be 'stepped-down' before being used by consumers?
400 000V is an unsafe and therefore not usable
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What happens when insulting materials are rubbed together?
Electrons will be rubbed off of one and transferred to the other (so they both become charged with equal positive static and negative static charges)
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Why are the static charges on two insulating materials that have been rubbed together equal?
The electrons transferred determine the charges: the electrons gained by one material dictate its positive charge, and the SAME NUMBER of electrons have been taken from the other material so it has an equal positive charge
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Why does a static objects can cause a shock or 'spark' to travel to the ground (ie. lighting)
As an electric charge builds on the object, the potential difference between the object and the earth increases (which is as 0V). At one point, the potential difference will be so great the electrons can 'jump' across the gap to the earth
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Why does a static object give you a shock or cause a 'spark' when touched?
The electric charge building on the object means the potential difference between the object and the earthed conductor (you) is large enough for the electrons to 'jump' and transfer through you to the ground.
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What happens when two electrically charged objects are brought close together?
They exert a non-contact force on one another
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Like charges _ Opposite charges _
repel, attract
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What is the movement of two charged objects by a non-contact force called?
Electrostatic attraction or repulsion
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True or false; any electrically charged object creates an electric field
True
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Is the electric field stronger closer or further from an electrically charged object?
Stronger when it is closer
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how can you show the electric field around an object?
Using field lines
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Which direction do electric field lines go?
From positive to negative
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Apart from direction positive-> negative what other rules are there about drawing field lines? (2 marks)
1. They are always at right angles to the surface 2. The closer together the lines are, the stronger the field
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Draw the diagram for the field lines of a positively charged sphere
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Draw the diagram for the field lines of a negatively charged sphere
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What causes the eletro-static repulsion/attraction felt by two charged objects in the same closeness?
The interaction of their electric field
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How can 'sparking' be explained by electric fields? (part 1)
The high potential difference between the earth and the charged object causes a strong electric field to be produced between the two. The field removes the electrons from the air participles (ionisation) and means the air is no longer an insulator.
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How can 'sparking' be explained by electric fields? (part 2)
The air becomes conductive instead and is able to carry the charge between the object and the earth (hence the spark)
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What is the equation for density? Include units
Density (kg/m^3) = Mass (kg) / Volume (m^3)
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What is density a measure of?
The compactness of a substance - relates mass of a substance with how much space it takes up
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What does the density of a material depend on? (2 marks)
1. What its made of 2. How the particles in it are arranged
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At a constant mass, what does decreasing the volume mean?
An increase in density (particles move closer together)
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Explain a solid in terms of (a) Density (b) Arrangement (c) Energy (d) Forces of attraction
Solids have a HIGH DENSITY, because their particles have little energy strong forces of attraction form between the particles. They are arranged in a regular lattice and the reduced energy means they can only vibrate.
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Explain a liquid in terms of (a) Density (b) Arrangement (c) Energy (d) Forces of attraction
Liquids are LESS DENSE than solids. Their particles have more energy than those in a solid and so have weaker forces of attraction forming between them and are able to move past each other. They move in random motion at slow speed.
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Explain a gas in terms of (a) Density (b) Arrangement (c) Energy (d) Forces of attraction
Gases have a very LOW DENSITY, because their particles have lots of energy, and no forces of attraction between each other and so are able to move in random motion at high speed.
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When does a change in state occur?
At the melting or boiling point of a substance - the point at which the substance is heated enough that the particles have enough energy in their kinetic energy stores to to break the bonds holding them together
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How is the energy in a system stored?
It is stored by its particles
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What is the internal energy of a system?
The total energy in the kinetic and potential energy stores of all the particles in the system.
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(In terms of energy stores) what happens when you heat a substance?
The particles in the substance gain energy in their kinetic energy stores, which increases the internal energy of the substance and makes the particles move faster
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A substance is heated and the temperature changes. What does the size of temperature change depend upon?
The specific heat capacity and size of energy input
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Is a change of state a physical change or a chemical change?
A physical change (no new substances formed and is easily reversible)
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The density of a material changes when it changes state. What is conserved?
Mass (the mass does not change in a change of state?
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What is specific latent heat?
The energy needed to change the state of 1kg of a substance
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Explain why on a temperature-time graph, lead's transition from solid to gas is flat at the point it melts and boils
When a substance is changing state, you are still putting energy in so the internal energy of the particles are increasing, but the temperature is not rising because the energy is used to break the inter-molecular bonds between particles
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What is the formula for specific latent heat? Include units.
SLH (J/kg) = Energy (J) / Mass (kg)
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How is average energy in the kinetic energy stores of gas particles related to temperature?
When a gas is heated, energy is transferred to the kinetic energy store of its particles. The higher the average temperature, the higher the average energy (and hence, average speed)
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What happens to the pressure of a gas at constant volume if temperature increases?
Increasing temperature means increased speed of random motion of particles. If particles move faster they will collide with surface and eachother more frequently and exert a force (or exert pressure). Therefore Net Pressure increases also.
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What happens to the pressure of a gas at constant mass AND temperature if volume increases?
The gas particles become more spread out (and constant temp means they are moving at the same speed) so they collide less frequently and the pressure of the gas decreases.
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What happens to the pressure of a gas at constant mass AND temperature if volume decreases?
The gas particles are pushed closer together and so collisions increase in frequency, this increases pressure
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What is Boyles Law of Gases?
Pressure (Pa) x Volume (m^3) = constant - true for a gas at constant mass and temperature
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What does Boyles Law dictate?
The pressure of a gas at a constant mass and temperature is inversely proportional to its volume.
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For an object with a flexible volume, how can an increase in pressure cause an increase in volume?
The pressure of a gas causes a net outward force at right angles to the surface of its container, if this is great enough, it can cause the container to expand
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Give an example of when work must be done on a gas to increase its temperature
Using a bike pump: you do work mechanically by doing work against the pressure of the gas acting on the bike pump. By pushing the plunger down, you are overcoming the force and transferring energy
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Explain the alpha scattering experiment and how it disproved the plum pudding model
Scientists fired alpha particles at gold foil, expecting them to go through or some be slightly deflected, however though most did go through, some were deflected and others deflects backwards. The plum pudding model could not explain this.
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Explain the alpha scattering experiment and how it resulted in Rutherford's atomic model
Scientists fired alpha particles at gold foil, expecting them to go through or some be slightly deflected, however though most did go through, some were deflected and others deflects backwards.
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Who first claimed the existence of energy levels?
Niels Bohr
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Who discovered the existence of neutrons?
James Chadwick
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What is the size of the radius of an atom?
1 x 10^-10 m
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How can electrons move energy levels?
By gain energy through absorption of EM radiation (mostly light) which allows them to 'jump' up energy levels. Losing this energy causes them to fall back down.
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What are isotopes?
Different forms of the same element with different numbers of neutrons
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True or False: all isotopes of elements are unstable
False, usually they are unstable but sometimes they are stable
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What is meant by an unstable isotope?
Unstable isotopes decay into other elements and give out radiation. This is called radioactive decay.
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What is ionising radiation?
Ionising radiation is a type of radiation given out during radioactive decay of unstable nuclei that is able to knock electrons off the outer shells of atoms and cause them to become positively charged.
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What types of ionising radiation exist?
Alpha, beta and gamma radiation
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Apart from giving out ionising radiation, how else do unstable nuclei become stable?
Giving out neutrons in an attempt to return to a balanced number of neutrons
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What is alpha radiation?
Alpha radiation is when an unstable nuclei gives out an alpha particle (or helium nuclei - two neutrons and two protons) symbol α
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What is the (a) penetrating power (b) range (c) ionising power of alpha radiation?
(a) They don't penetrate far and are stopped (absorbed) by paper (b) Range of only a few cm (c) Because of their size they are strongly ionising
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What is beta radiation?
Beta radiation is a fast-moving electron emitted by a nucleus where a neutron has turned into a proton and the emitted electron. Symbol β
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What is the (a) penetrating power (b) range (c) ionising power of beta radiation?
(a) Moderately penetrating but stopped by a sheet of aluminium (b) Their range is a few metres (c) They moderately ionising
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What is gamma radiation?
Gamma radiation is EM gamma radiation emitted by an unstable nuclei. Symbol γ
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What is the (a) penetrating power (b) range (c) ionising power of gamma radiation?
(a) Can penetrate far into materials but stopped by thick sheets of lead or concrete (b) Has infinite range (c) Not very ionising
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What form are nuclear equations written in?
Atom before decay -> atom after decay + radiation emitted
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What must be balanced for nuclear equations?
Total mass and atomic numbers
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Write the nuclear equation for the decay of Uranium (atomic number 92, mass number 238) by emission of alpha radiation
U -> Th + He
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Write the nuclear equation for the decay of Carbon-14 (atomic number 6) by emission of beta radiation
C -> N + e
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How can radiation be measured?
With a Geiger-Muller tube and counter which records count-rate
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What is count-rate?
the number of radiation counts per second
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True or false; Radioactive decay is completely random?
True
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What is half-life?
The time taken for the amount of radiation emitted by the source to halve / the time taken for the number of the radioactive nuclei in a substance to halve.
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How can half-life be used to find the activity of a radioactive substance?
Half-life can be used to find the rate at which a source decays (activity) where Activity (Becquerels Bq) = Decay /Time (seconds) and 1Bq = 1 decay per second
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True or false; the activity of a radioactive material can be zero
False, the activity of a radioactive material will never be zero
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What is the formula for finding the count rate after n lives?
Initial count rate / 2^n
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What is background radiation?
Background radiation is the low level radiation around us all the time
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What is meant when you are said to be 'irradiated'?
You are exposed to radiation (this does no make you radioactive)
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What can you do to reduce irradiation?
Keep sources in lead-lined boxes, stand behind barriers etc
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What is radioactive contamination?
Unwanted radioactive particles being transferred to an object.
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What does the seriousness of irradiation and contamination depend upon?
1. Exposure time and distance 2. Source of emission
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Is it more damaging to be irradiated by alpha radiation or gamma and beta radiation?
Gamma and beta radiation because they have a high penetrating power (alpha particles can't penetrate very far into the body)
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Is it more damaging to be contaminated by alpha radiation or gamma and beta radiation?
Alpha radiation because it acts on very localised areas (absorbed over a small surface area) and are very ionising (do a lot of damage) - beta and alpha are not as ionising and absorbed over larger surface area.
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What is the difference in the damage caused by (1) low doses of ionising radiation (2) high doses of ionising radiation
(1) Causes tissue damage and gives rise to mutant cells which divide to cause cancerous tumours (2) High doses can kill cells, causing radiation sickness (vomiting, tiredness)
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How can gamma radiation be used in medicine?
Gamma-emitting isotopes can be used as tracers to check bodily activity ie. isotope iodine-123 can absorbed by the thyroid like iodine-127 to check if it is absorbing iodine as it should. The isotopes are injected or swallowed.
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What is radiotherapy?
Using radiation to treat cancer (a) Gamma rays directly carefully at cancer cells (b) Beta-emitting implants put next to cancer cells
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What is perceived risk?
how risky someone thinks something is
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What is nuclear fission?
Nuclear fission is when a large unstable nucleus absorbs a neutron and splits to form two new lighter elements (with increased amount of kinetic energy in their stores) and also two or three neutrons - any extra is carried away by gamma rays
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How can the process of nuclear fission be used to generate electricity?
Energy from gamma rays can be used to heat water, making steam to turn turbines and generators.
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What is fission chain reaction?
The fission of an unstable nucleus causes two/three neutrons to be emitted, this can go on to be absorbed by another unstable nucleus and cause nuclear fission.
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How can we control how much energy is produced in a nuclear reactor?
By controlling the rate of the chain reaction using control rods that are lowered and raised (when lowered they absorb neutrons)
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How can fission chain reactions explain nuclear weaponry?
Uncontrolled nuclear fission leads to a lot of energy being released at one time as an explosion.
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What is nuclear fusion?
Two small lightweight nuclei colliding at high speed and fusing together. The mass of the heavier nucleus formed is not as great as the two lightweight nuclei: some of the mass is converted to energy carried away as radiation.
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Which releases more energy; fusion or fission?
Fusion
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Why don't we have fusion reactors?
The pressure and temperature needed are too high (too dangerous and expensive to build)
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What happens to the energy in a system if the system changes?

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The way the energy is stored changes

Card 3

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What is a closed system?

Back

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Card 4

Front

What are the eight types of energy store?

Back

Preview of the front of card 4

Card 5

Front

In what five ways can energy be transferred?

Back

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