AQA GCSE Physics Questions and Answers 2023 paper 1

AQA GCSE Physics Questions and Answers 2023 paper 1 Energy Stores 1) Elastic potential 2) Gravitational potential 3) Thermal 4) Electrostatic 5) Nuclear 6) Chemical 7) Kinetic 8) Magnetic 9) Light 10) Sound How is energy transferred? 1) Mechanically - force doing work 2) Electrically - work done by moving charges 3) Heating/Radiation - light, sound How can work be done? When a current flows or by a force moving an object Kinetic energy formula E=1/2mv² Kinetic energy(J) = 0.5 x mass(kg) x speed²(m/s) Gravitational potential energy formula E=mgh G.P.E(J) = mass(kg) x gravitational field strength (N/kg) x height (m) What happens when an object falls and there's no air resistance? Energy lost from the g.p.e store = energy gained in the kinetic energy store What does air resistance do when acting against falling objects? It causes some energy to be transferred to other energy stores e.g. the thermal energy stores of the object and the surroundings Elastic potential energy formula E=1/2ke² E.P.E(J) = 0.5 x spring constant(N/m) x extension²(m) What is SHC? The amount of energy needed to raise the temperature of 1kg of a substance by 1°C SHC formula E=mcθ Change in thermal energy(J) = mass(kg) x SHC(J/kg/°C) x temperature change(°C) What is the conservation of energy principle? Energy can be transferred usefully, or stored or dissipated (wasted energy), but can never be created or destroyed What is power? The rate of energy transfer, or the rate of doing work What is 1W equal to? 1J of energy transferred per second Power Equation 1 E=Pt Energy transferred(J) = power(W) x time(s) Power Equation 2 W=Pt Work done(J) = power(W) x time(s) What is conduction? The process where vibrating particles transfer energy to neighbouring particles Energy is transferred to thermal stores of the object - this energy is shared across the kinetic energy stores What is thermal conductivity? A measure of how quickly energy is transferred through a material via conduction What is convection? Where energetic particles move away from hotter to cooler regions Energy is transferred to the thermal energy stores of the object and is shared across the kinetic stores What do radiators create? Convection currents Convection currents - process 1) Energy is transferred from the radiator to the nearby air particles by conduction 2) The air by the radiator becomes warmer and less dense as the particles move quicker 3) The warm air rises and displaces the cooler air, which is then heated by the radiator 4) The previously heated air transfers energy to the surroundings - the air cools, becomes denser and sinks What does lubrication do? Reduce frictional forces What does insulation do? Reduce the rate of energy transfer by heating Thermal insulation techniques 1) Cavity walls - made up of an inner and outer wall with an air gap in the middle - the air gap reduces the amount of energy transferred by conduction through the walls 2) Cavity wall insulators - the air gap is filled with foam also reduces energy transfer by convection in the wall cavity 3) Loft insulation - reduces convection currents being created in lofts 4) Double-glazed windows - air gap between two sheets of glass that prevent energy transfer by conduction through the windows 5) Draught excluders - reduce energy transfers by convection around doors and windows How do you improve efficiency? 1) Lubrication 2) Insulation 3) Making objects more streamlined Efficiency - energy transfer equation Useful output energy transfer divided by total input energy transfer Efficiency - power equation Useful power output divided by total power input Is any device 100% efficienct? No Where is wasted energy usually transferred? Thermal energy stores How do thick walls prevent energy losses through heating? They're made from a material with a low thermal conductivity - the thicker the walls, the lower the thermal conductivity, the slower the rate of energy transfer What objects are usually 100% efficient? Electric heaters - all the energy in the electrostatic energy stores is transferred to useful thermal energy stores Fossil fuels (coal, oil, natural gas) Non-renewable Cause acid rain Cause global warming Reliable currently - they are finite, so they will run out eventually Coal mining ruins the landscape Oil spillages cause serious environmental problems Energy resources used for transport Petrol and diesel from oil - non-renewable Coal (steam trains) - non-renewable Bio-fuels - renewable Energy resources used for heating Natural gas - non-renewable Coal - non-renewable Electric heaters - non-renewable Geothermal - renewable Solar water heaters - renewable Bio-fuels - renewable Wind Power Renewable Doesn't cause global warming Doesn't cause acid rain No pollution No permanent damage to the landscape Free - initial costs are high Very noisy Spoil the view Not always reliable Solar Power Renewable Doesn't cause acid rain Doesn't cause global warming No pollution Free - solar panels are expensive though Not always reliable Geothermal Power Renewable Doesn't cause acid rain Doesn't cause global warming Free Very little damage to the environment Not very reliable - can only happen in certain places and there aren't very many of them Hydroelectric Power Renewable Reliable Doesn't cause acid rain Doesn't cause global warming No pollution Provides an immediate response to high demand Free - initial cost is high Big impact on environment and possible loss of habitat Wave Power Renewable Doesn't cause acid rain Doesn't cause global warming Free - initial costs are high Not always reliable - waves die out when the wind drops Disturbs the seabed and habitats of marine wildlife Spoils the view Hazard to boats Tidal Power Renewable Reliable Doesn't cause acid rain Doesn't cause global warming No pollution Free - initial costs are moderately high Spoils the view Alters the habitats of wildlife Bio-fuels Renewable Reliable Doesn't cause acid rain Carbon neutral Free Can cause global warming Loss of natural habitat from destruction of forests Cannot respond to immediate energy demands Nuclear Power (Uranium or Plutonium) Doesn't cause acid rain Doesn't cause global warming Reliable currently - finite Non-renewable High decommissioning costs Produces radioactive waste - no other pollution Nuclear waste is dangerous and hard to dispose of Investigating Specific Heat Capacities - Method 1) Measure the mass of a block with two holes in it, then wrap it in an insulating layer (e.g. newspaper) to reduce the energy transferred from the block to the surroundings. Insert the thermometer into one hole and the heater into another 2) Measure the initial temperature of the block & set the potential difference of the power supply to be 10V. Turn on the power supply & start a stopwatch 3) When you turn on the power, the current in the circuit does work on the heater, transferring energy electrically from the power supply to the heater's thermal energy stores - this energy is then transferred to the material's thermal energy store by heating, causing its temperature to increase 4) As the block heats up, take readings of the temperature and current every minute for 10 minutes - the current shouldn't change 5) Turn off the power supply. Use the measurements of the current & the p.d. to calculate the power supplied to the heater, thus calculating how much energy has been transferred to the heater at the time of each temperature reading 6) If you assume all the energy supplied to the heater has been transferred to the block, you can plot a graph of energy transferred to the thermal energy store of the block against temperature Investigating the Effectiveness of Materials as Thermal Insulators - Method 1) Boil water in a kettle. Pour some of the water into a sealable container to a safe level. Measure the mass of water in the container 2) Use a thermometer to measure the initial temperature of the water 3) Seal the container & leave it for 5 minutes. Measure this time using a stopwatch 4) Remove the lid & measure the final temperature of the water 5) Pour away the water & allow the container to cool to room temperature 6) Repeat this experiment, but wrap the container in a different material once it has been sealed. Ensure the mass of water is the same and so is the initial temperature each time What is a closed system? A system where neither matter nor energy can enter or leave Why did electricity use in the 20th century increase? 1) The population grew 2) People began to use electricity for more & more things Why did electricity use in the 21st century decrease? 1) Appliances are becoming more efficient 2) We're more careful with energy use in our homes Why are we trying to increase our use of renewable energy resources? 1) Burning fossil fuels is damaging to the environment 2) Non-renewables will run out one day 3) Pressure from other countries & the public has led to targets being set e.g the UK aims to use renewable resources to provide 15% of the total yearly energy by 2020 What has pressure from the public & other countries led to? Pressure being put on energy providers to build new power plants that use renewable resources to ensure that they don't lose business & money What is the use of renewables limited by? 1) Reliability - since some energy resources aren't that reliable, a combination of different power plants would have to be used - expensive 2) Money - building new power plants costs money, the cost of switching to renewable power will have to be paid & some people don't want to or can't afford to pay 3) Politics - companies and governments can't force people to change their behaviour What happens when a system changes? Energy is transferred - it can be transferred into/away from the system, between different objects in the system or between different types of energy stores Why are wind turbines unlikely to be able to power everything in the UK? 1) Large numbers of turbines would need to be built - takes up space & is expensive 2) Not always windy - the same amount of electrical power won't be produced every day What is electric current? The flow of electrical charge What is electric current measured in? Amps What is potential difference? Voltage - it pushes the electric charge around the circuit What is potential difference measured in? Volts What is resistance? Anything that slows the flow down What is resistance measured in? Ohms The greater the resistance... ...the smaller the current that flows What is the formula for charge? Charge (coulombs) = current (amps) x time (seconds) Q=It What is the formula for Pd? Potential difference (volts) = Current (amps) x Resistance (ohms) V=IR The longer the wire... ...the greater the resistance Is the ammeter placed in series or parallel? Series Is the voltmeter placed in series or parallel? Parallel Do Ohmic Conductors have a constant resistance? Yes - at a constant temperature, the current is directly proportional to the potential difference What does resistance change in? Diodes and filament lamps Why does resistance increase with temperature in a filament lamp? When the electrical charge flows through the lamp, it transfers some energy to the thermal energy stores of the filament which is designed to heat up. Therefore, the resistance, temperature and current all increase Resistance is directly proportional to temperature What is an LDR? Light Dependent Resistor - a resistant dependent on the intensity of light In bright light, the resistance decreases In darkness, the resistance is highest What is a thermistor? A temperature dependent resistor In hot conditions, the resistance decreases In cold conditions, the resistance increases What happens to Pd in a series circuit? It's shared between all the components What happens to current in a series circuit? The current is the same in all components What happens to resistance in a series circuit? The total resistance is the sum of all the resistances What happens to Pd in a parallel circuit? The Pd is the same in all components What happens to current in a parallel circuit? The current is shared between the components, therefore the total current is found by adding up the currents of all the components What happens to resistance in a parallel circuit? If you have two resistors parallel, their total resistance is less than the resistance of the smallest of the two resistors Mains supply is... AC - Alternating current Battery supply is... DC - Direct Current Alternating Current The current is constantly changing direction Alternating currents are produced by alternating voltages in which the positive and negative ends keep alternating UK Mains Supply Voltage 230V UK Frequency of AC 50Hz (hertz) Direct Current Current is always flowing in the same direction Created by a direct voltage Live Wire Brown colour Bottom right of the three pin plug Provides the alternating pd from the mains supply - 230V Current flows in through this wire Neutral Wire Blue colour Bottom left of the three pin plug Completes the circuit and carries away current Electricity flows out through this wire Around 0V Earth Wire Green and yellow colour Middle of the three pin plug Protects the wiring Stops the casing from becoming live Doesn't usually carry a current - only when there's a fault Around 0V Equation - Energy transferred 1 Energy transferred (J) = Power (W) x Time (s) E=Pt A 600W microwave is used for 5 minutes. How long (in minutes) would a 750W microwave take to do the same amount of work 1) 600 x (5 x 60) = 180,000J or 180kJ 2) 180,000J = 750W x t 3) t = 180,000J/750W 4) t = 240s = 4 minutes The lower the power rating... ...The less electricity an appliance uses in a given time, therefore it is cheaper to run Equation - Energy Transferred 2 Energy transferred (J) = Charge flow (C) x Potential difference (V) E=QV The motor in an electric toothbrush is attached to a 3V battery. 140C of charge passes through the circuit as it is used. Calculate the energy transferred 1) E=QV 2) E= 140C x 3V 3) E = 420J Equation - Power 1 Power (W) = Potential difference (V) x Current (A) P=VI Equation - Power 2 P=I²xR Power = current² x resistance A 1.0kW hair dryer is connected to a 230V supply. Calculate the current through the hair dryer. Give your answer to two significant figures I=P/V I= 1000/230 I=4.3A What is the National Grid? A giant system of cables and transformers that covers the UK and connects power stations to consumers When does demand for electricity increase? When it starts to get dark or cold outside When people get up in the morning When people come home from school or work What is the problem with a high current? You lose loads of energy as the wires heat up and energy is transferred to the thermal energy stores of the surroundings What's the cheaper way of transmitting power? High potential difference and low current - decreases the energy lost by heating the wire and the surroundings How is static electricity caused? Friction - when two things rub against each other, electrons from one will rub off on to the other One material will have a positive static charge (e.g. acetate) and the other will have a negative static charge (e.g. polythene) What subatomic particle moves? Electrons Positive charges never move - a positive charge is achieved when electrons move away What increases with a build up of electric charge? The potential difference between the object and the earth What is the spark? When the electrons jump across the gap between the charged particle and the earth if the potential difference becomes too large How big is the gap for the spark to happen? Usually fairly small (lightning is an exception) What is created around an electrically charged object? An electric field The closer to the object... ...The stronger the electric field. The stronger it is, the higher the potential difference is What is the force between two charged objects near to each other caused by? Their electric fields interacting with each other What is ionisation? When a strong electric field causes electrons in the air particles to be removed What happens when air is ionised? It becomes much more conductive and so a current can pass through it (a spark) What is an RCCB? Residual Current Circuit Breaker Protects some circuits Detects a difference in the current between the live and neutral wires Works faster than fuses Double insulation Used for appliances without an earth wire Have plastic casings Designed so that the live wire cannot touch the casing Cannot give an electric shock The Fuse Thin piece of wire which melts if too much current passes through it When the wire melts, all current is stopped and the appliance is switched off What does the switch do? Controls the amount of current that enters an appliance with the fuse Symbol - Cell Symbol - Battery Symbol - Switch Symbol - Filament lamp/Bulb Symbol - Fuse Symbol - LED Symbol - Resistor Symbol - Variable resistor Symbol - Ammeter Symbol - Voltmeter Symbol - Diode (Other way around) Symbol - LDR Symbol - Thermistor Investigating Resistance - Method 1) Attach a crocodile clip to the wire level with 0cm on the ruler 2) Attach the second crocodile clip to the wire e.g. 10cm away from the first clip. Write down the length of the wire between the clips 3) Close the switch, then record the current through the wire & the p.d. across it 4) Open the switch, then move the second crocodile clip another e.g. 10cm along the wire. Close the switch again then record the new length, current & p.d. 5) Repeat this for a number of different lengths of the test wire 6) Calculate the resistance for each length of wire & plot a graph of resistance against wire length. Draw a line of best fit Finding a Component's I-V Characteristics - Method 1) Set up the test circuit with a battery, ammeter, component, voltmeter & variable resistor 2) Begin to vary the variable resistor - alters the current flowing through the circuit & the p.d. across the component 3) Take several pairs of readings from the ammeter & voltmeter to see how the p.d. across the component varies as the current changes - repeat each reading twice more to get an average p.d. 4) Swap over the wires connected to the cell, so the direction of the current is reversed 5) Plot a graph of current against voltage for the component I-V Characteristics - Diode Current will only flow through a diode in one direction. The diode has a very high resistance in the reverse direction I-V Characteristics - Filament Lamp As the current increases, the temperature of the filament increases, so the resistance increases Less current can flow per unit p.d., so the graph gets shallower I-V Characteristics - Ohmic Conductor The current is directly proportional to potential difference, therefore you get a straight line Investigating Series Circuits - Method 1) Build a circuit with an ammeter, a battery & one of four identical resistors. Make a note of the potential difference of the battery 2) Measure the current through the circuit using the ammeter - use this to calculate the resistance 3) Add another resistor, in series, with the first 4) Again, measure the current through the circuit & use this & the pd. of the battery to calculate the overall resistance of the circuit 5) Repeat steps 3 & 4 until all the resistors have been added 6) Plot a graph of the number of resistors against the total resistance of the circuit Investigating Parallel Circuits - Method 1) Build a circuit with an ammeter, a battery & one of four identical resistors. Make a note of the potential difference of the battery 2) Measure the total current through the circuit & calculate the resistance 3) Add another resistor, in parallel, with the first 4) Measure the total current through the circuit & use this & the p.d. of the battery to calculate the overall resistance of the circuit 5) Repeat steps 3 & 4 until all the resistors have been added 6) Plot a graph of the number of resistors against the total resistance What are sensing circuits? They're used to turn on or increase the power to components depending on the conditions that they are in What is the maximum operating power? The maximum safe power an appliance can operate at Series circuits If you remove/disconnect a component, the circuit is broken and they all stop - not very useful Parallel circuits If you remove/disconnect a component, it will hardly affect the others - useful for most things e.g. cars, household electrics What is the core of a wire made out of? Copper What is electrostatic attraction/repulsion? Forces that cause objects to move Electric field lines Go from positive to negative Always at a right angle to the surface The closer together the lines are, the stronger the field is Is air normally a conductor or an insulator? An insulator Why does potential difference change across the thermistor as the temperature decreases? Pd increases because the thermistor's resistance increases What is the formula for density? Density = mass/volume What are the units for density? kg/m³ What are the three states of matter? Solid, liquid and gas Describe the arrangement of particles for each state Solid - particles are in a fixed position and vibrate Liquid - particles are in a random arrangement and move slowly Gas - particles are in a random arrangement and move quickly Describe how you could find the volume of an irregular solid object For an irregular solid, you can find is volume by submerging it in a eureka can filled with water. The water displaced by the object will be transferred to the measuring cylinder.