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Download A level Physics Edexcel Paper 3 Questions And Answers 2025/2026 and more Exams Physics in PDF only on Docsity!
A level Physics Edexcel Paper cstions And Answers 2025/2026 g by free-fall method - correct Answ- Drop object using electromagnet - Measure time and distance - Use suvat to get g mnemonic for exam questions - correct AnswSyllables of experiment e = equation p= procedures i= improvements m = math analysis g by free-fall light gate vs stopwatch - correct Answlight gate prevents human reaction time random errors stop watches rely on human reaction time Light gates will have a smaller percentage uncertainty g by free-fall problems with air resistance - correct AnswCreates a systematic error as direction of air resistance will make value lower chan true value g by free-fall graphical analysis - correct Answput suvat equation into y = mx + c to get a straight line Gradient is useful as it takes less account of anomalies Resistivity of a metal method - correct Answ- Measure resistance of various lengths of wire - Measure diameter of the wire - Use equation to find resistivity Resistivity of a metal using a ohmmeter directly or using a voltmeter and ammeter - correct AnswUsing a voltmeter and ammeter will provide better resolution however will create more uncertainty V/I = R Obmmeters are quicker to measure Resistivity of a metal and the usefulness of a multimeter - correct AnswAllows to measure variable resolutions, allowing you to Measure to the ideal 3 sig fig Systematic Errors in the Resistivity of a metal - correct Answ- Potential heating of wire if too much current is passed through, resistance is dependant on temperature - Non-zero resistance in a circuit will shift graph (but not affect gradient) Resistivity of a metal and using a micrometer - correct AnswCan measure 0.01 of a millimetre ‘Lake multiple readings of diameter, discard anomalies and take an average to reduce random error and uncertainty - Consider weight, upthrust and Stoke's force to calculate viscosity Falling ball viscometer problems with light gates - correct AnswLiquid blocks the beam and it would be difficult to get the ball to fall directly through the beam and therefore its not always appropriate to use this type of measurement to for an accurate timing Falling ball viscometer improvements - correct Answ- Works bet with smaller balls and more viscous fluids as accurate timing is difficult - Use video analysis instead of a stopwatch - Increase values of reading to reduce uncertainty - Use a wide tank as stokes law doesn't consider extra drag with being near to the edge of a measuring cylinder Young Modulus of Copper method - correct Answ- Measure diameter and original length ofa copper wire - stretch the wire with increasing force measure it's extension - plot a stress over strain graph to get the young modulus Young modulus of copper measuring extension - correct Answ- You need a long wire greater than 2m so extension is large enough to be measured - Or you need a very small cross sectional area to allow for larger extension - Vernier calipers can be used to measure small extensions Percentage uncertainty in extension is likely to be very large because of the measurement Young modulus of copper measuring diameter - correct AnswMeasure diameter twice at right angles to each other and repeat 5 times along the length of the wire and take an average to reduce random errors Young modulus of copper sig figs - correct AnswAlways give final results to the same number of significant figures as the least significant figures that were measured to Speed of sound method - correct Answ- Compare the electrical signal with the sound wave it produces onan oscilloscope - Record points where the microphone signal is in phase wich the electrical signal, these points are one wavelength apart - Measure frequency using oscilloscope and use the wave speed equation to calculate the speed of sound, Speed of sound getting waves in phase - correct Answlt is difficult to know as microphone signals can have interference leading to a thick trace in addition is reduces in amplitude as you get further from the loudspeaker Speed of sound time base - correct AnswWe can adjust the time base to get a high resolution of time period reducing uncertainty of the frequency calculated Speed of sound measuring on wavelength - correct AnswUse a fixed ruler and set square to line up a certain point on the microphone The frequency chosen needs to give a wavelength in the region of 10cm as this is easy to measure with a ruler and will keep uncertainties low - They produce bight spot maxima even at long distances, reducing uncertainty Diffraction grating using white light - correct AnswWhite light is not monochromatic as its maxima would be a spectrum making it very difficult to accurately measure the distances between maxima Error - correct AnswThe difference between the measured and actual result Uncertainty - correct Answthe interval/ range in which the (true) value can be considered to lie Resolution - correct AnswThe smallest division on an instrument Zero Error - correct AnswAny indication that a measuring system gives a false reading when the true value of a measured quantity is zero and will result in a systematic uncertainty Parallax error - correct AnswError caused. by not having your eye directly in line with the measurement How to get a straight line from a power law equation - correct AnswR = kdAp ‘Lake logs from both side compare to y = mx +c R=kd’p InR = p x Ind + Ink y=mxt+e Logs must be correct to 4 sig figs When quo Vernier Caliper - correct Answinstrument used for measuring precise linear dimensions 0.05 of a milimeter resolution Why when measuring a diameter or radius the uncertainty will be high - correct AnswBecause it will be doubles when used to find an area A= pir42 Why does measuring means reduce uncertainty? - correct Answlt reduces the likelihood of random error What do you do if you are asked to calculate the smallest value? - correct AnswRearrange the equation to have the answer as the value If it is dividing by a value make it bigger, if it is multiplying make it smaller What must you do before taking count rate from a source? - correct AnswTake count of background radiation Subtract from count for specified time Divide the count by that time to get count rate Systematic Error - correct AnswErrors in the experimental method or equipment when readings are consistently too big or too small e.g. zero erros Precision - correct AnswA reflection of how close multiple measurements are to one another Accuracy - correct AnswA description of how close a measurement is to the crue value of the quantity measured. Fiducial Markers - correct Answfixed reference points against which other objects can be measured Why do we take means? - correct Answ'l'o reduce the effect of random errors and spot anomalies Describe how to use a stopwatch to determine time period of an osscilation - correct AnswRecord. the time 10 oscillations and divide the measurement by 10 to get the time for 1 oscillation this reduces the effects of random error How to derive non SI units - correct Answ1. write down equation for unit Work Done = F x D 2, Write down units of equation Work Done = Nx m 3. Simplify any non SI units Work Done = kgms‘-2 x m 4, Simplify final units Work Done kem*-1s4-2 radians to degrees conversion - correct Answmultiply by 180/x degrees to radians conversion - correct Answmultiply by 2/180 SI base units - correct Answmeter, kilogram, second, kelvin, mole, ampere, candela Scalar - correct AnswA physical quantity that has magnitude only. Vector - correct AnswA quantity that has magnitude and direction Scalar examples - correct Answl)istance Speed. Energy mass time Vector Examples - correct AnswDisplacement Velocity Acceleration Magnetic fields and aluminium rings staying in position - correct Answ- ‘I'he current produces a magnetic field around the aluminium - the direction of the ring field opposes the change producing it - the fields repel, producing a fore - the electromagnetic force is equal and opposite to the weight of the ring so it remains in position shown Comment on maximum height measurement as a means of determining an accurate value for the launch speed - correct AnswAir resistance dissipates energy which will slow launch speed Elastic Deformation - correct AnswReturns back to original shape after deforming force is removed A resultant force causes - correct AnswAcceleration Plastic Deformation - correct AnswWill not return back to original shape after deforming force is removed Gravitational field strength is inversely proportional to - correct Answr squared Conditions for simple harmonic motion - correct Answ- Force is directed to the centre (equilibrium)/ acts opposite to displacement - This is proportional to displacement How to get a straight light from a power law equation - correct AnswR = kd4p Take logs from both side compare to y = mx +c R=kd’p InR = p x Ind + Ink y=mxt+e Logs must be correct to 4 sig figs When quo How to put log values ina table - correct AnswLogs values must be correct to 4 sig figs Table units are quoted as Ln(Length/m) What must you do when plotting a graph - correct Answ- Axis must be over half the paper to minimise uncertainties - line of best fit - draw large triangle {to minimise uncertainties) to calculate a gradient Electron Gun Model Answer - correct Answ- Low voltage supply heats filament causes thermionic emission/ electrons have enough energy to leave ~ Electrons are repulsed from the cathode (filament) and attracted towards the anode Why does the photoelectric effect equation refer to kinetic energy as maximum kinetic energy? - correct Answlt will not always be an equal energy transfer: - Some energy may have been transferred to electrons below the surface - Therefore for these electrons to liberate to the surface there will be heat transfer through collision ~ therefore the electrons leaves the surface will less than max Energy Frequency equation - correct AnswE = hf E = energy h = plank's constant f = frequency Work function equation - correct AnswWork Function = h x threshold frequency Work Function - correct Answthe minimum energy needed to liberate an electron from a metal atom Threshold Frequency - correct Answminimum light frequency necessary to liberate an electron from a given metal Energy is proportional to frequency Wave Particle Duality Model Answer - correct Answ Nuclear Binding Energy - correct Answ'l‘he energy needed to separate a nucleus into individual protons and neutrons E = mcA2 Binding Energy = mass difference x the speed of light*2 How to calculate nuclear binding energy from a nuclear decay equation? - correct AnswTh -> Ra +a Mass of Th nuclear-(Mass of Ra nuclear + mass of alpha particle) Convert u to kg Multiply by speed of light*2 E = mc*2 Convert to Mev How to convert u to kg - correct Answkg / 1,6605x10*-27 How to convert kg to u- correct Answkg / 1,6605x10*-27 Whar is 1 u? - correct Answ1.6605x10%-27kg Converting u to Mev - correct Answu x 931.5 Converting Mev to u - correct AnswMev / 931.5 - enormous temperatures We need these to get two nuclei close enough together to fuse - Containment using magnetic fields uses more energy than the reaction yields We need this because it is the only way to contain plasma from container walls Binding energy per nucleon curve - correct AnswAll reaction through fission or fusion aim to get to iron 56 because it is the most stable element Absorption Spectra - correct Answa spectrum of electromagnetic radiation transmitted through a substance, showing dark lines or bands due to absorption of specific wavelengths. How is an absorption/ emission spectrum produced? - correct AnswShining white light through a sample of a gaseous element The samples of the emission spectrum, (the wavelengths missing from the absorption spectrum) area result of the absorption of energy by electrons corresponding to the energy levels of the element by the gas Emission Spectrum - correct Answa spectrum of the electromagnetic radiation emitted by a source, showing coloured lines due to the emission of the wavelengths Atomic Line Spectra Model Answer - correct Answ- All elements and their isotopes have a line spectrum ~The spectra are the wavelengths absorbed or emitted from an element with an electron gains or looses energy - The energy is lost in the form of photons of certain wavelengths backround radiation - correct Answnuclear radiation that occurs naturally in the environment Examples of background radiation - correct Answ- cosmic radiation - radioactive elements - radioactive substances ~ rocks - living things - air How to account of background radiation? - correct AnswMeasure background count Subtract this from radioactive element count Nucleon number - correct Answthe total number of protons and neutrons in the nucleus of an atom Mass number - correct Answthe sum of the number of neutrons and protons in an atomic nucleus Proton number - correct Answthe number of protons in the nucleus of an atom Atomic number - correct Answthe number of protons in the nucleus of an atom How to find mass number? - correct Answprotons + neutrons 
