Higher Physics Particles And Waves Notes
nuclear.GravitationalForce particleRangeRelative StrengthGravitonInfinite1(not yet verified)This is the weakest of the four forces. It holds matter in planets, starsand galaxies together.ElectromagneticForce particleRangeRelative StrengthPhotonInfinite1036This is a combination of the electrostatic and magnetic forces. This holdselectrons within atoms.Weak Nuclear ForceForce particleRangeRelative Strength-18W and Z bosons10 m1025This is weak relative to the strong nuclear force. It is involved inradioactive beta decay and is experienced in quark and leptoninteractions.Strong Nuclear ForceForce particleRangeRelative Strength-15Gluon10 m1038This holds protons together in the nucleus of an atom – without thiselectrostatic theory predicts that they would fly apart. This is onlyexperienced by quarks.The Higgs boson is not involved in forces, but is what gives particlesmass. This is not part of the Higher course.The standard model9
The standard modelBeta decay - neutrinosWhen there is beta decay a neutron decays into a proton.and an electron.The electron is emitted and the nucleus is left with a net positive charge,however, this does not follow the law of conservation of momentum.The electron is forced out athigh speed due to the nuclearforces, carrying away kineticenergy and momentum.pu d ueW-A down quark mustdecay into an up quarkthrough the emission u d dof aboson.nExample 5Physicists study subatomic particles using particle accelerators.Pions are subatomic particles made up of two quarks.There are two types of pion:anda.b.c.particles which have a charge of 1,particles which have a charge of -1,particles which have a zero charge.Theparticle is made up of an up quark and an anti-down quark.Is a pion classified as a baryon or a meson?Justify your answer.The charge on an up quark is 2/3.Determine the charge on an anti-down quark.Theparticle is the antiparticle of theparticle.State the names of the quarks that make up aparticle.(a) Meson because it is made of two quarks.(b) 1 2/3 charge on anti-down 1/3(c) “anti-up” and “down”The standard model10
The standard modelExample 6a) Explain why particles such as leptons and quarks are known asFundamental particles.b) A particle called the sigma plus (Σ ) has a charge of 1. Itcontains two different types of quark. It has two up quarkseach having a charge of 2/3 and one strange quark. What isthe charge on the strange quark?c) Explain why the gluon cannot be the force mediating particlefor the gravitational force.a)These particles cannot be broken down (into other subparticles)b)For the sigma plus particle2 x ( 2/3) qs 1qs -1/3Charge on strange quark -1/3c)Strong force (associated with the gluon) acts over a veryshort distance. The gravitational force extends over verylarge/infinite distances.The standard model11PW Problem booklet 1P3 Q 1 - 7
Learning Outcomes – Forces on Charged Particles.This builds on information from Electricity and Energy Potential difference (voltage)At the end of this unit you should be able to:o State that charged particles experience a force in an electricfield.o State that forces exist round charged particles and betweencharged parallel plateso Draw the field patterns foro single point chargeso systems of two point chargeso between two charged parallel plates.o Describe the direction of movement of charged particles in anelectric fieldo Define the volt using the relationship between potentialdifference, work and charge.o Carry out calculations using the relationship W QVo Use W QV and Ek ½ mv2 to solve problems involving the charge,mass, speed and energy of a charged particle in an electric fieldand the potential difference through which it moves. (Useconservation of energy to calculate the speed of a charged particleaccelerated by an electric field)o State that a moving charge produces a magnetic field.o Determine the direction of the force on a charged particle movingin a magnetic field for both negative and positive charges (forexample using the right hand rule for negative charges)o Describe the basic operation of particle accelerators in terms ofo acceleration of charged particleso deflection of charged particleso collision of charged particles.Forces on charged particles12
Electric FieldsAn electric field exists around a charged object. We cannot see the fieldbut we can see its effect on objects.A positive test chargewill move away from apositive point chargeand towards anegative point charge. negative point chargepositive point chargeAn electric field is three dimensional – but we draw it as two dimensional forsimplicity. Where the field is stronger the lines are drawn closer together. -Two like charges – same size, justmake sure the arrows are drawn inthe correct direction.Two unlike charges – same sizeUniform electric field. Use a ruler Space the lines evenlyForces on charged particles 13
Movement of Charged Particles -A positively charged particle,placed in a uniform electricfield, will move towards thenegative plateA negatively charged particle,placed in a uniform electricfield, will move towards thepositive plateAn electric field exerts a force on a charged particle. When it ismoving the energy can be calculated using Ek ½ mv2.If the particle is moved against the direction of the force the energyis stored as electric potential energy.Ew QVOne volt one joule per coulombDefinition of the voltThe potential difference (p.d.) between two points is one volt if onejoule of energy is used to move one coulomb of charge between thosetwo points.Example 7A student writes the following statements about electric fields.IThere is a force on a charge in an electric fieldIIWhen an electric field is applied to a conductor, the freeelectric charges in the conductor move.III Work is done when a charge is moved in an electric field.Which of the above statements is true?AI onlyBII onlyCI and II onlyDI and III onlyEI, II and IIISQA 2004 Higher Q10EForces on charged particles14
Movement of Charged ParticlesExample 8The electric field patterns around charged particles Q, R and S areshown. Identify the charge on each particle.Q – positiveR – positiveS - negativeSQA revised H 2014Q8 adaptedExample 9An electron is accelerated from rest through a potential differenceof 2.0 kV.The kinetic energy gained by the electron isA8.0 x 10-23JB8.0 x 10-20JC3.2 x 10-19JD1.6 x 10-16JE3.2 x 10-16JEExample 10A potential difference, V, is applied between two metal plates. Theplates are 0.15m apart. A charge of 4.0 mC is released from rest atthe positively charged plate as shown.The kinetic energy of the charge just before it hits the negative plateis 8.0 J.The potential difference between the plates is .A3.2 x 10-2VB1.2 VC2.0 VD2.0 x 103VE4.0 x 103VDForces on charged particles[Type text]15[Type text][Type text]
Movement of Charged ParticlesExample 11The apparatus shown in in the diagram is designed to accelerate alphaparticles.An alpha particle travelling at a speed of 2.60 x 106 ms-1 passes througha hole in plate A. The mass of an alpha particle is 6.64 x 10-27 kg and itscharge is 3.2 x 10-19C.(a)When the alpha particle reaches plate B, its kinetic energyhas increased to 3.05 x 10-14 J.Show that the work done on the alpha particle as it movesfrom plate A to plate B is 8.1 x 10-15J(b)Calculate the potential difference between plates A and B.(c)The apparatus is now adapted to accelerate electrons from Ato B through the same potential difference.How does the increase in the kinetic energy of an electroncompare with the increase in kinetic energy of the alphaparticle in part (a)?Justify your answer.(a)(b)(c) ½ mv2 ½ x 6.64 x 10-27 x (2.60 x 106)2 2.24 x 10-14JIncrease in Ek work done between the plates 3.05 x 10-14 - 2.24 x 10-14 8.1 x 10-15JEw QVV 8.1 x 10-15 2.5 x 104 V3.2 x 10-19Same potential differenceBut the charge is smaller.So less work is doneSo smaller (increase in ) kinetic energy.At A, EkForces on charged particles16
Practical Uses of Electrical FieldsIf an object is charged it can attract small particles - a charged plasticruler can attract pieces of tissue paper. This can be put to practical usein cleaning ash from exhaust gases in power stations or in paint spraying.Electrostatic precipitationAsh particles are attracted to the wire and clump together, they thenfall out the bottom where they can be removed. Clean air exits at the top.Paint sprayingThe object beingpainted is earthed.Paint particles arecharged by the highvoltage supply andare attracted to theobject, even paintingthe back.Forces on charged particles17
Practical Uses of Electrical FieldsExample 12A machine to help move threads in a modern weaving machine usesbeads of oil and two metal plates X and Y.The potential difference between these plates is 5.0 x 103 V.Each bead of oil has a mass of 4.0 x 10-5 kg and is given a negativecharge of 6.5 x 10-6C.The bead accelerates from rest at plate X and passes through a holein plate Y. 5 x 103 V0Vmetalplates-6.5 x 10-6Cbead of oilcharged bead of oilplate Xplate YNeglecting air friction, calculating the speed of the bead at plateY.Ew QV 6.5 x 10-6 x 5 x 103 3.25 x 10-2 JEk ½ mv23.25 x 10-2 ½ x 4.0 x 10-5 x v2v 40.3 ms-1SQA Higher 2001 Q23 (b)Example 13An electron is accelerated across a potential difference (p.d.) of700V. Calculate the maximum speed the electron reaches.Charge on an electron 1.6 x 10-19 CMass of an electron 9.11 x 10-31 kgEw QV 1.6 x 10-19 x 700Assume all Ep isconverted to EkEk1.12 x 10-16 1.12 x 10-16 Jv ½ mv2 ½ x 9.11 x 10-31 x v2 1.6 x 107 ms-1Forces on charged particles18PW Problem booklet 1P5 Q 1 - 9
Moving Charge and Magnetic Fields – Predicting MotionWhen current flows through a wire a magnetic field is producedaround the wire.The direction current flows through a wireis represented by the tip or the flights ofan arrowMFCRight hand motor ruleThis is used to predict thedirection of movement whenthere is a current in amagnetic field.First finger Field (N S)SeCond finger Current(electron flow)ThuMb MovementNXXXXXSXXXXXXXXXXXXXXXXXXXXElectrons travelling upElectrons travelling upMagnetic field fromleft to right.Electrons will curveout of the page dueto the field.Magnetic field goinginto the page.Electrons will curveto the right due tothe field.Forces on charged particles19
Moving Charge and Magnetic Fields – Predicting MotionRotating coilField coilSplit ringcommutatorCarbonbrushesA motor depends on the interaction between two magnetic fields. Thecoil in the centre of the motor is an electromagnet. When currentflows through the rotating coil its magnetic field interacts with thefield from the field magnet (which can be permanent or anelectromagnet).Where there are like poles the rotating coil is repelled. This makes itspin.The commutator makes current flow in the correct direction to keepthe motor spinning. The brushes allow the current to reach thecommutator.Example 14An electron enters a region of magnetic field as shown.The direction of the force exerted by the magnetic field on theelectron as it enters the field is .SQA revised H 2014Towards the bottom of the page.Q9 adaptedForces on charged particles20PW Problem booklet 1P7 Q 1 - 4
Particle AcceleratorsParticle accelerators are used to increase the velocity of particles sothat when they are collided they break down into fundamentalparticles. They can also be used to treat cancer.Linac – Linear AcceleratorAs is suggested by the name charged particles are accelerated in avacuum pipe through as series of electodes by an alternating voltage.Advantage – simple accelerationDisadvantage – must be very, very long to accelerate particles to highenergy states.CyclotronCharged particles start off atthe centre. Electrodes areshaped like the letter ‘D’ andare called ‘dees’. A magneticfield causes the particle tomove in a circular path. Eachtime the particle moves fromone dee to another itaccelerates and moves to aslightly larger orbit. When itspirals to the outer edge it isextracted for use.SynchrotronThe synchrotron can bethought of as a circular linearaccelerator. Magnets are usedto keep the charged particlesin the centre of theaccelerator. The Large HadronCollider at CERN is an exampleof a particle accelerator.Forces on charged particles21
Particle AcceleratorsExample 15A cyclotron is used in a hospital to accelerate protons that are thentargeted to kill cancer cells.The cyclotron consists of two D-shaped hollow metal structures called‘dees’, placed in a vacuum. The diagram shows the cyclotron viewedfrom above.Protons are released from rest at R and are accelerated across thegap between the ‘dees’ by a voltage of 55 kV.(a)(i) Show that the work done on a proton as it acceleratesfrom R to S is 8.8 x 10-15 J.(ii) Calculate the speed of a proton as it reaches S.(b)Inside the ‘dees’ a uniform magnetic field acts on theprotons. Determine the direction of this field.(c)Explain why an alternating voltage is used in the cyclotron.(a)(b)(c)(i) E QV 1.6 x 10-19 x 55000 8.8 x 10-15 J(ii) Ek ½ mv2 ½ x 1.673 x 10-27 x v2v 3.2 x 106ms-1Into the page or down/downwards but not down thepage.A.c. voltage used to chage the direction of the forceon protons/polarity of the dees/electric field acrossthe gap.ORElectric field must change direction to acceleratethe protons because the direction the protons crossthe gap changes/keeps changingSQA revised H 2013 Q 26Forces on charged particles22
Particle AcceleratorsExample 16The electron volt (eV) is a unit of energy. It represents the change inpotential energy of an electron that moves through a potentialdifference of 1V (the size of the charge on an electron is 1.6 x 10-19C.What is the equivalent energy of 1eV in joules?Ew QV 1.6 x 10-19 x 1 1.6 x 10-19 JExample 17(a)In the Large Hadron Collider (LHC) beams of hadrons travelin opposite directions inside a circular accelerator and thencollide. The accelerating particles are guided around thecollider using strong magnetic fields.(i) The diagram shows a proton entering a magnetic fieldIn which direction is this proton deflected?(ii) The neutron is classified as a hadron.Explain why neutrons are not used for collisionexperiments at the LHC.Explain how particle accelerators, such as the LHC at CERNare able to(i) accelerate charged particles(ii) deflect charged particles.(b)(a)(b)(i) deflected downwards (not South)(ii) neutrons don’t carry/have charge, so cannot beaccelerated/guided/deflected by magnetic fields(i) electric field (to accelerate)(ii) magnetic field (to deflect)SQA revised H 2012 Q26 (d), 2014 Q26 (b)Forces on charged particles23PW Problem booklet 1P9 Q 1 - 11
Nuclear Reactions – Learning OutcomesThis builds on information from Waves and RadiationNuclear radiation At the end of this section you should be able toooooooooWrite nuclear reactions to describe radioactive decay for Alpha radioactive decay Beta radioactive decay Gamma radioactive decayUse nuclear equations to calculate the original element whichhas undergone a series of radioactive decaysUse nuclear equations to predict the element produced by aseries of radioactive decaysIdentify spontaneous fission, induced fission and fusionreaction from a nuclear equationCalculate the mass loss in a nuclear reactionUse E mc2 to calculate the energy released by a nuclearreaction by calculating the mass loss in both fission and fusionreactionsExplain, in words, what happens when fission and fusionreactions take place.Describe what is meant by coolant and containment issues innuclear fusion reactors.Nuclear reactions24
Model of the atomThe nucleus of the atomcontains both protons andneutrons. It has an overallpositive charge. Most of themass of the atom isconcentrated at the centre ofthe atom.Electrons are around theoutside of the atom.Mass number Number of protons number of neutronsAtomic number Number of protonsA - Mass numberZ - Atomic numberUraniumAtoms which have the sameatomic number but differentmass numbers are calledisotoPes.To find the number ofneutrons in an atomMass number – atomic number238 – 92 146Alpha DecayUranium ThoriumBeta DecayProtactiniumUraniumChemicalsymbolAlpha decay is when an alpha particle (2protons and 2 neutrons, equivalent to aHelium nucleus) is lost from an atom.Beta decay is where a neutron changesinto a proton and electron. The protonstays in the atom, but the electron andan antineutrino is emitted.Gamma DecayGamma rays are photons of electromagnetic radiation, not particles.When gamma rays are emitted from an atom this does not change themass number of atomic number of the atom.Nuclear reactions25
Nuclear Reactions – emitting radiationIt is possible to predict the type of radiation emitted during aradioactive decay by looking at the mass number and the atomic number1. If the mass number goes down by 4 and the atomic number goesdown by 2 it is alpha radiation.2. If the mass number stays the same and the atomic number goes upby 1 it is beta radiation.3. If the mass number stays the same and the atomic number staysthe same it is possible that gamma radiation has been emitted, butthere is no way to tell, so the picture is incomplete.Example 18Identify the missing particles or nuclides represented by the lettersA, B, C and tiniumThalliumReactions can follow on from one another in a radioactive ‘daisy chain’ asshown below.Example 19Identify the type of radiation released at each stage of the followingradioactive chain reaction.U 23892Th 23490UraniumThoriumPa 23491Protactinium23492UUraniumUsing the information about which type of radiation was emitted,identify the element at the start of the reaction (including mass andatomic numbers).BismuthNuclear reactionsPolonium26Lead
Nuclear Fission CalculationsA series of nuclear reactions can also be represented in a gridMass number239235231X2227 X422489 90X1X3919293Atomic numberThis could also be written asUraniumThoriumProtactiniumActiniumwhere an alpha particle is emitted going from X1 to X2 and from X3 to X4 ,and a beta particle is emitted going from X2 to X3.It isn’t possible to tell whether gamma radiation is emitted or not fromthe diagram.Nuclear Fission (break apart)Nuclear fission can either be spontaneous or stimulated.a) Spontaneous nuclear fissionA large atomic nucleus splits into two nuclei of smaller massnumber plus several free neutrons, releasing energy.FermiumXenonPalladiumneutronsb) Stimulated nuclear fissionA large atomic nucleus is induced by bombarding it with neutrons, itsplits into two nuclei of smaller mass number plus several freeneutrons, releasing energy.Neutron UraniumBariumKryptonneutronsNuclear FusionIn nuclear fusion, two small atomic nuclei combine to form a largernucleus, releasing energy. Other small particles such as neutrons may alsobe formed.Hydrogen HydrogenNuclear reactionsHelium neutron27
Nuclear Fission CalculationsIn nuclear fission reactions – both spontaneous and stimulated - mass isalways lost during the reaction. This ‘lost mass’ is converted into kineticenergy of the products using Einstein’s famous equationE mc2whereE energy (J)m mass (kg)c speed of light (3 x 108 ms-1)Example 20A nuclear fission reaction is represented by the following statement.(i)(ii)(iii)(iv)Is this a spontaneous or an induced reaction ? You must justifyyour answer.Determine the numbers represented by the letters r and s inthe above reaction.Use the periodic table to identify the element represented byT.The masses of the nuclei and particles in the reaction are givenbelowMass (kg)390.219 x 10-27227.292 x 10-27157.562 x 10-271.675 x 10-27Calculate the energy released in the reaction.(i)Induced – a neutron is added to the left hand side.(ii)r 55 s 95(iii)Element T Rubidium(iv)Left hand sideRight hand side390.219227.292 1.675157.562-27391.894 x 10 kg (4 x 1.675)391.554 x 10-27kgLoss in massE mc2391.894 0.34 x 10-27 x (3 x 108)2- 391.554 3.06 x 10-11J SQA H 2006 Q 29 (b)0.34 x10-27kgNuclear reactions28
Nuclear Fusion CalculationsIn nuclear fusion reactions mass is always lost during the reaction. This‘lost mass’ is converted into kinetic energy of the products usingEinstein’s famous equationE mc2whereE energy (J)m mass (kg)c speed of light (3 x 108 ms-1)Example 21The sun releases its energy through vast numbers of hydrogen nucleifusing into helium every second. Calculate the energy released by oneof these reactions, shown below.Deuterium tritium α particle neutronMass (kg)3.345 x 10-275.008 x 10-276.647 x 10-271.675 x 10-27Left hand side3.345 x 10-27 5.008 x 10-278.353 x 10-27 kgRight hand side6.647 x 10-27 1.675 x 10-278.322 x 10-27 kgMass difference8.353 x 10-27- 8.322 x 10-270.031 x 10-27kgEnergy releasedE mc2 0.031 x 10-27 x (3 x 108)2 2.8 x 10-12JNuclear reactions29
Nuclear Fusion – the fuel of the future?The hydrogen bomb is an example of an uncontrolled nuclear fusionreaction.To use fusion as an energy source the reaction needs to be controlled.To sustain fusion there are three conditions, which must be metsimultaneously Plasma temperature must be 100 – 200 million Kelvin. At thistemperature the molecules of a gas will lose electrons to becomepositively charged ions.A stable reaction lasting at least 5 seconds called the EnergyConfinement Time 4 – 6 secondsA precise value for the density of plasma 1-2 particles m-3(approximately 1mg m-3 i.e. one millionth the density of air)Containing the extremely hot plasma isdone using magnetic fields in the shape of atorus (doughnut). Two magnetic fields areneeded – the toroidal direction is thecircumference of the doughnut, thepoloidal direction is the circumference of aslice of the doughnutIt takes a lot of energy to raise the temper
particles and interactions. Provide evidence supporting the existence of sub-nuclear particles and the existence of antimatter. State that fermions, the matter particles, consist of quarks (six types) and leptons (electron, muon, tau, together with the
Quantum Physics Particles act like waves! Particles (electrons, protons, nuclei, atoms, . . . ) interfere like classical waves, i.e., wave-like behavior Particles have only certain "allowed energies" like waves on a piano The Schrodinger equation for quantum waves describes it all. Quantum tunneling Particles can "tunnel" through walls!
electromagnetic waves, like radio waves, microwaves, light, and x-rays are examples of transverse waves. Longitudinal waves travel through a medium in a direction parallel to the direction of travel of the wave. Mechanical waves such as sound waves, seismic waves created by earthquakes, and explosions are all examples of longitudinal waves.
Q: What are mechanical waves? A: Waves that require a medium in which to travel. A medium is the _ that waves travel through o Mediums can be solid, liquid, or gas Examples of mechanical waves include sound waves, seismic waves, ocean waves, etc Q: Describe two types of mechanical waves.
College physics Semester 2 Unit 2 What is a wave? How do they act? How are do waves differ? 1/29 Pre-test Waves on a String. Notes: Introduction to Waves . Lab: Waves on a String Activity (PhET) Do: read 12.3 p457 (1,3,5) 1/30 Clicker questions: Waves on a String. Lab: Fourier-Making Waves part 1 (PhET) 2/1 Lab: Fourier-Making Waves part 2 (PhET)
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Physics 20 General College Physics (PHYS 104). Camosun College Physics 20 General Elementary Physics (PHYS 20). Medicine Hat College Physics 20 Physics (ASP 114). NAIT Physics 20 Radiology (Z-HO9 A408). Red River College Physics 20 Physics (PHYS 184). Saskatchewan Polytechnic (SIAST) Physics 20 Physics (PHYS 184). Physics (PHYS 182).
Waves and Thermodynamics MASTERING PHSICS 3.4 Electromagnetic Waves Conduct investigations to explain and analyse differences between mechanical and electromagnetic waves. Electromagnetic waves Electromagnetic transverse waves are different from transverse matter waves in that they: Can travel through a vacuum.
electromagnetic waves we can see. We see these waves as the colors of the rainbow. Each color has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they make white light. Visible light waves are the only electromagnetic waves we can see.
