IB Questionbank Physics11.Light of frequency f is incident on a metal surface. The work function of the metal is . Which of the following is the maximum kinetic energy of the electrons emitted from the surface?A.hf B.C. hfD.(Total 1 mark) 2.An electron is accelerated from rest through a potential difference V.Which of the following is the de Broglie wavelength of the electron after acceleration?A.B.C.D.(Total 1 mark)3.Which of the following is an assumption of the Schrdinger model of the hydrogen atom?A.The orbital path of the electron fits a standing wave.B.The position of the electron is undefined but its momentum is well defined.C.The momentum of the electron is undefined but its position is well defined.D.The electron is described by wavefunctions.(Total 1 mark) 4.A Bainbridge mass spectrometer may be used to measure the mass ofA.an atom.B.an ion.C.an isotope.D.a molecule.(Total 1 mark) 5.A nucleus of the isotope potassium-40 decays to a nucleus of the isotope argon-40. The reaction equation for this decay may be written asWhich of the following correctly identifies the proton number of argon-40 and the particle X?ZXA.18B.18+C.19+D.19(Total 1 mark)6.An alpha particle is accelerated through a potential difference of 10 kV. Its gain in kinetic energy isA.10 eV.B.20 eV.C.10 keV.D.20 keV.(Total 1 mark) 7.The GeigerMarsden experiment provides evidence forA.the existence of discrete atomic energy levels.B.the existence of the neutron.C.a dense positively charged nucleus.D.the stability of some nuclei.(Total 1 mark) 8.A radioactive isotope has a half-life of two minutes. A sample contains sixteen grams of the isotope. How much time elapses until one gram of the isotope remains?A.6 minutesB.8 minutesC.10 minutesD.12 minutes(Total 1 mark)9.Which of the following decay sequences would result in the daughter nucleus having the same proton number as the parent nucleus?A.Alpha followed by gammaB.Beta ( ) followed by gammaC.Alpha followed by beta () followed by beta ()D.Beta () followed by gamma followed by gamma(Total 1 mark) 10.The difference between the mass of a nucleus and the sum of the masses of the individual nucleons is 0.1 u. Which of the following is approximately the binding energy of the nucleus?A.90 MeVB.90 MeV c2C.8 MeVD.8 MeV c2(Total 1 mark) 11.The process by which a heavy nucleus splits into two lighter nuclei is known asA.fission.B.fusion.C.radioactive decay.D.artificial (induced) transmutation.(Total 1 mark)12.This question is about nuclear processes.(a)A nucleus of radium-91 () undergoes alpha particle decay to form a nucleus of radon (Rn).(i)Identify the proton number and nucleon number of the nucleus of Rn.Proton number: .................................................................................................Nucleon number: ..............................................................................................(2) (ii)The half-life of radium-91 is 1600 years. Determine the length of time taken for 87.5% of the radium to disintegrate..................................................................................................................................................................................................................................................................................................................................................................................(2) (b)Immediately after the decay of a stationary radium nucleus, the alpha particle and the radon nucleus move off in opposite directions and at different speeds.Outline the reasons for these observations.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)Outline why a beta particle has a longer range in air than an alpha particle of the same energy.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 10 marks) 13.This question is about the wave nature of matter.(a)Describe the de Broglie hypothesis...................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)Outline an experiment to verify the de Broglie hypothesis...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3) (c)Show that the de Broglie wavelength of electrons accelerated from rest through a potential difference of 150 V is 1.0 1010 m.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 8 marks)14.This question is about alpha () particle scattering.An experiment is carried out in which alpha () particles of initial kinetic energy 5.0 MeV are fired at a piece of gold foil. The proton number of gold is 79.Determine the distance of closest approach of an alpha () particle to a gold nucleus.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(Total 4 marks) 15.This question is about + (positron) decay.(a)In a + decay, a positron is emitted along with a neutrino, and a -ray photon.Although the energy spectrum for -rays involved is discrete, the energy spectrum for the positrons is continuous.(i)State the difference between a discrete energy spectrum and a continuous energy spectrum.......................................................................................................................................................................................................................................................(1)(ii)Explain how the existence of the neutrino accounts for the continuous nature of the positron energy spectrum.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2) (b)Sodium-22 is a radioisotope used in nuclear medicine that undergoes + decay.The half-life of sodium-22 is 2.6 years.A sample of sodium-22 has an initial activity of 6.2 109 Bq.(i)Define decay constant.......................................................................................................................................................................................................................................................(1) (ii)Calculate the decay constant of sodium-22.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(1)(iii)Calculate the activity of the sample of sodium-22 after 8.0 years...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 8 marks) 16.This question is about fundamental interactions.(a)State an exchange particle for(i)the weak interaction............................................................................................................................(1) (ii)the electromagnetic interaction............................................................................................................................(1) (b)Comment, with reference to the mass of the exchange particles, on the range of the weak and electromagnetic interactions.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(c)Describe the process represented by the Feynman diagram below...................................................................................................................................................................................................................................................................................................................................................................................................................(1) (d)State what is meant by a virtual particle.............................................................................................................................................................................................................................................................................(1) (e)Explain how the Heisenberg uncertainty principle for energy and time applies to the interaction in (c)...................................................................................................................................................................................................................................................................................................................................................................................................................(2)(f)The uncertainty in the time for the electromagnetic interaction between two electrons is 1.6 1016 s. Determine the uncertainty in the energy of the virtual photon...................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 10 marks) 17.This question is about nuclear decay and ionization.(a)A nucleus of radium-91 () undergoes alpha particle decay to form a nucleus of radon (Rn).Identify the proton number and nucleon number of the nucleus of Rn.Proton number: ............................................................................................................Nucleon number: .........................................................................................................(2) (b)Immediately after the decay of a stationary radium nucleus, the alpha particle and the radon nucleus move off in opposite directions and at different speeds.(i)Outline the reasons for these observations...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3) (ii)Show that the ratiois about 56...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3) (c)The initial kinetic energy of the alpha particle is 4.9 MeV. As the alpha particle passes through air, it loses all its kinetic energy by causing the ionization of 1.7 105 air molecules.(i)State what is meant by ionization.......................................................................................................................................................................................................................................................(1)(ii)Estimate, in joules, the average energy needed to ionize an air molecule.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2) (d)Outline why a beta particle has a longer range in air than an alpha particle of the same energy.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 14 marks)18.This question is about the hydrogen atom.(a)A parallel beam of visible light is shone through monatomic hydrogen gas.The radiation emerging from the gas is analysed by comparing the incident and emerging intensities at various wavelengths. It is found that at a wavelength of 490 nm the intensity of the emergent beam is greatly reduced.The diagram shows some of the electron energy states of the hydrogen atom where n is the quantum number of the energy level. (i)Calculate the energy, in eV, of a photon of light of wavelength 490 nm.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)Use your answer in (a)(i) and the energy level diagram to explain the reduction in intensity of the emergent beam...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(4) (b)Outline how the Schrdinger model of the hydrogen atom leads to the idea of discrete electron energy states.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(4)(Total 10 marks)19.This question is about radioactive decay and binding energy.(a)Describe what is meant by radioactive decay.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2) (b)A nucleus of thallium-206 (Tl-206) undergoes radioactive decay to a nucleus of lead-206 (Pb-206). In the reaction equation below, identify the proton number Z of lead and the particle x.Z: .................................................................................................................................x: .................................................................................................................................(2) (c)The mass of a Tl-206 nucleus is 191 870 MeV c2. Determine the binding energy per nucleon of Tl-206.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(4)(d)State why the binding energy of Pb-206 is greater than that of Tl-206...................................................................................................................................................................................................................................................................................................................................................................................................................(1)(Total 9 marks) 20.This question is about the photoelectric effect.(a)In the photoelectric effect, electrons are emitted from a metal surface almost immediately after light is incident on the surface, i.e. without any time delay. Explain this observation with reference to Einsteins theory of the photoelectric effect...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)The graph shows the variation with incident light frequency f of the maximum kinetic energy EK of the emitted electrons. Use the graph to(i)estimate the work function of the metal surface.......................................................................................................................................................................................................................................................(1) (ii)calculate the maximum speed of the emitted electrons for incident light of frequency 5.0 1015 Hz.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 6 marks)21.This question is about quantum aspects of the electron.(a)The energy of electrons in atoms is said to be quantized. State what is meant by quantized energy.............................................................................................................................................................................................................................................................................(1) (b)An electron that is confined to move in a region of length L can only have energies given by the equationEn = where n is a positive integer. For L = 1.0 1010 m, use the equation above to(i)calculate that the smallest difference between the allowed energies of the electron is 5.8 1018 J..................................................................................................................................................................................................................................................................................................................................................................................(2) (ii)determine the wavelength of the photon whose energy is 5.8 1018 J........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)Part of the emission spectrum of hydrogen is shown in the diagram.Suggest whether this spectrum can be explained by the model in (b).........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 8 marks) 22.This question is about radioactive decay.(a)The decay constant for a particular isotope is = 0.048 s1. A sample of the isotope initially contains 2.0 1012 nuclei of this isotope.(i)Define decay constant.......................................................................................................................................................................................................................................................(1) (ii)Estimate the number of nuclei that will decay in the first second.......................................................................................................................................................................................................................................................(1)(b)The graph shows the variation with time t of the activity A of a sample containing radioactive material that consists of two different isotopes. Each isotope decays into a stable daughter isotope. (i)Use the graph to explain how it may be deduced that the sample contains more than one isotope.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)One of the isotopes in the sample has a half-life that is shorter than 0.20 s. Use the graph to estimate the half-life of the other isotope. Explain your working.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 6 marks) 23.This question is about radioactive decay and binding energy.(a)Describe what is meant by radioactive decay.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2) (b)A nucleus of potassium-40 (K-40) undergoes radioactive decay to a nucleus of argon-40 (Ar-40). In the reaction equation below, identify the proton number Z of argon and the particle x.Z: .................................................................................................................................x: .................................................................................................................................(2)(c)The mass of a K-40 nucleus is 37 216 MeV c2. Determine the binding energy per nucleon of K-40...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(4) (d)State why the binding energy of Ar-40 is greater than that of K-40.............................................................................................................................................................................................................................................................................(1)(Total 9 marks)24.This question is about radioactive decay.(a)The alpha particles produced in alpha decay have discrete energies. Suggest how this observation provides evidence for the existence of nuclear energy levels.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)A nucleus of the isotope fluorine-18 decays into a nucleus of oxygen-18 by the emission of a positron and neutrino. Outline how the nature of the -decay energy spectrum of fluorine-18 suggests the existence of the neutrino involved in the decay...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3) (c)A freshly prepared sample of fluorine-18 has an activity of 1.12 MBq. Its activity four hours later is 0.246 MBq.(i)Show that the decay constant for fluorine-18 is 0.379 hr1........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(ii)Calculate the half-life of fluorine-18.......................................................................................................................................................................................................................................................(1) (d)The energy of a beta particle in the decay of the sample in (c) is 8.4 1015 J. Show that the de Broglie wavelength of this particle is 5.3 1012 m.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 11 marks) 25.A[1] 26.A[1] 27.D[1] 28.B[1] 29.B[1]30.D[1] 31.C[1] 32.B[1] 33.C[1] 34.A[1] 35.A[1] 36.(a)(i)proton number: 89;nucleon number: 222;2 (ii)12.5% remains;3 half lives 4800 years;2 (b)momentum conserved;so different speeds as different masses;opposite directions because momentum zero initially;3 (c)beta have smaller mass / smaller / have greater speed than alpha;beta have smaller charge than alpha;therefore less likely to interact with air molecules;3[10]37.(a)all particles have an associated wavelength / OWTTE;wavelength is given by , where h is Plancks constantand p is momentum;2 (b)(beam of) electrons accelerated through a potentialdifference (in a vacuum);incident on (nickel) crystal;scattered beam shows maxima and minima (at specificpositions of detector);3Above points could be indicated in a diagram such as the one below: (c)EK = eV = ; = ; = ; = 1.0 1010 m3[8] 38.using conservation of energy, Initial EK = EP;EK = 5.0 MeV =5.0 1.6 1013 = 8.0 1013 J;EP = ;d = 4.6 1014 m;4Accept answers that combine any of the above steps.[4] 39.(a)(i)in a discrete energy spectrum, the energy is restricted tocertain values / in a continuous energy spectrum, theenergy can take on any value / OWTTE;1 (ii)total energy of decay is constant;energy is shared between positron and neutrino;2 (b)(i)the probability of decay of a nucleus per unit time;Accept ln 2/T provided T is identified as the half-life.1 (ii) = = 0.27 yr1 or 8.5 109 s1;1 (iii)A = A0et;= 6.2 109 e0.278.0;= 7.2 108 Bq;3[8] 40.(a)(i)W+/W/Z0 (boson);1Do not insist on superscripts. (ii)photon / ;1 (b)range of interaction is inversely proportional to mass of exchangeparticle / range of interaction is given by with symbols defined;bosons have mass, photons do not, hence range ofelectromagnetic interaction is infinite, range of weak interactionis finite / OWTTE;2 (c)electromagnetic interaction between two electrons / electron-electronscattering / collision of electron with electron;1 (d)a particle that appears as an intermediate particle in a Feynmandiagram / a particle that is not (directly) observed / (temporarily)violates energy/momentum conservation;1(e)Et with symbols defined;virtual photon can exist, temporarily breaching energyconservation, for a time that depends on its energy;2 (f)E = ; = 3.3 1019 J;2[10] 41.(a)(i)proton number: 89;nucleon number: 222;2 (b)(i)momentum conserved;so different speeds as different masses;opposite directions because momentum zero initially;3 (ii)k.e. k.e.Rn = mv2 mRnvRn2 / sensible ratio formed;= (mv)2mRn (mRnvRn)2m / cancellation of momentum terms;= mRn m = (= 55.5);3Award [3] for correct answer obtained by alternative correctworking.Watch for ecf from (a) e.g. leads to 56.5 for answer here. (c)(i)removal (addition) of electron from atom/molecule;1 (ii);4.6 1018 J;2 (d)beta have smaller mass / smaller / have greater speed than alpha;beta have smaller charge than alpha;therefore less likely to interact with air molecules;3[14] 42.(a)(i)eV = energy = 2.5 eV;2 (ii)490nm excites energy level transitions;from n = 2 to n = 4;energy removed from beam;re-emitted in other directions/at other wavelengths aselectrons returned to energy state;4 (b)Schrdinger suggests that electron has wave properties;this (probability) wave has to conform to boundary conditions;only certain wavelengths that lead to a standing wave areallowed (by these boundary conditions);energy is determined by wavelength of electron / standing wavedetermines electron energy;4[10] 43.(a)unstable nuclei/nuclides change spontaneously/randomly/emit energy;by the emission of alpha particles and/or electrons and/or gammarays; (accept , and particles/radiation)2To award [2 max] reference must be made to nuclei/nuclides andto spontaneously/ randomly. (b)Z: 18 or 20;x: neutrino/ v / /antineutrino/ / ;2Please note: that + decay is not in the SL core, only so acceptanswers in terms of decay and mark any combination correct. (c)mass of 81 protons = (81 938 =) 75978 MeV c2;mass of 125 neutrons = (125 940 =) 117500 MeV c2;mass difference = 75978 + 117500 191870 = 1608 MeV c2;binding energy per nucleon = 7.81 MeV;4 (d)energy is released in the decay of Tl-206 / energy released isthe difference in binding energies / decay is spontaneous / Pb-206is more stable than Tl-206;1[9] 44.(a)light arrives at the surface as photons, each carrying an energy hf;electrons will absorb this energy at one step and so will be emittedimmediately / single event, no energy accumulates;2 (b)(i)(by extrapolating the line) = 1.6 1019 J;(accept answers in the range of 1.5 to 1.8)1 (ii)kinetic energy is EK = 1.7 1019 J;(accept answers in the range of 1.6 to 1.8)and so v = ;v = 6.1 105 m s1;3[6] 45.(a)energy that takes certain values and not others / energy valuesthat are not continuous / energies that give rise to a discreet/line spectrum / transition energies are discreet / OWTTE;1 (b)(i)choice of levels n = 1 and n = 2;Emin = ;Emin = 5.8 1018 J2The formula has been quoted on the paper. However,accept the use of the formula quoted in the booklet,correctly not including , leading to a Emin of 1.8 1017 J. (ii) = 5.8 1018 J;hence = 3.4 108 m;3Use of 1.8 1017 J leads to a of 1.1 108 m. (c)no it cannot;because the box spectrum has spectral lines crowding in theinfrared rather than in the ultraviolet as in the real H spectrum;Accept any other plausible explanation e.g. the box modeldoes not take into account any electrical potential energyor the hydrogen atom is not one-dimensional or thehydrogen atom is not a box etc.Award [0] for a bald no and/or a no with an incorrect explanation.2[8]46.(a)(i)the probability of decay per unit time (of a particularnucleus) / the constant of proportionality betweenactivity and number of nuclei present;1 (ii)expected number to decay is (approximately)2.0 1012 0.048 = 9.6 l010;1ornumber decayed is N = 2.0 1012 [l e0.048] = 9.4 1010;Accept either numerical answer. The first estimate is approximate;the discrepancy between the two answers becomes negligibleas the decay constant becomes smaller. (b)(i)(with one isotope present), after each half-life, half theradioactive nuclei would be decaying;and this is not the case here;2 (ii)finding time for number of nuclei to reduce by half byusing the extreme right part of the curve which ismainly due to the decay of the other isotope;to get approximately 0.70 s; (accept answers in therange of 0.65 to 0.75 s)2[6] 47.(a)unstable nuclei/nuclides change spontaneously/randomly/emit energy;by the emission of alpha particles and/or electrons and/orgamma rays; (accept , and particles/radiation)2To award [2 max] reference must be made to nuclei/nuclidesand to spontaneously randomly. (b)Z: 18;x: neutrino/ v/;2 (c)mass of 19 protons = (19 938 =) 17822 MeV c2;mass of 21 neutrons = (21 940 =) 19740 MeV c2;mass difference = 17822 + 19740 37216 = 346 MeV c2;binding energy per nucleon = 8.65MeV;4Allow answer in joule, 1.38 1012 J.(d)energy is released in the decay of K-40 / energy released is thedifference in binding energies / decay is spontaneous / A-40is more stable than K-40;1[9] 48.(a)the different alpha particle energies represent decay of a nucleusto different energy states of a daughter nucleus;since the energies of the alpha are discreet it means that theenergy levels of the daughter nucleus must be discrete / OWTTE;2 (b)the spectrum is continuous;with a maximum value of energy;the resulting energy difference between energy of any and maximum energy is accounted for by the energy of theneutrino / reference to energy difference between parent energylevel and excited energy level of daughter;3 (c)(i)0.246 = 1.12e4.00;4.00 = ln 0.2196(*); = (*);(*) (evidence of algebraic manipulation)= 0.379 hr13Note: there are [2] marks for clearly showing their working (ii)1.83 hr;1 (d) = ;= ;= 5.3 1012 mAccept solution based on finding momentum from the speed.2[11]