aqa a level old spec categorized questions, Exams of Physics

Download aqa a level old spec categorized questions and more Exams Physics in PDF only on Docsity!

Exampro A-level Physics

3.2.1.3 Particles, antiparticles and

photons

Name: Class:

Author:

Date:

Time: 137

Marks: 112

Comments

Q1. Neutrons were discovered when beryllium, Be, was bombarded with alpha particles. An alpha particle knocked a neutron out of a beryllium nucleus producing a carbon nucleus, C. (a) Write down the equation that describes this reaction. ........................................................................................................................ (2) (b) (i) Describe the quark substructure of a neutron. ............................................................................................................... ............................................................................................................... (1) (ii) Describe how the quark substructure of a meson differs from that of a baryon such as a neutron. ............................................................................................................... (1) (Total 4 marks) Q2. (a) State the name of the antiparticle of a positron. ........................................................................................................................ (1) (b) Describe what happens when a positron and its antiparticle meet. ........................................................................................................................ ........................................................................................................................ (2) (Total 3 marks)

Sketch on Figure 1 the path you would expect the protons to take. Figure 1 (iii) Explain why protons take a different path to that of the positrons. ............................................................................................................... ............................................................................................................... ............................................................................................................... ............................................................................................................... ............................................................................................................... ............................................................................................................... (5) (b) Figure 2 shows five isotopes of carbon plotted on a grid in which the vertical axis represents the neutron number N and the horizontal axis represents the proton number Z. Two of the isotopes are stable, one is a beta minus emitter and two are positron emitters.

Figure 2 (i) Which isotope is a beta minus emitter? ............................................................................................................... (ii) Which of the two positron emitters has the shorter half-life? Give a reason for your choice. ............................................................................................................... ............................................................................................................... ............................................................................................................... (3) (c) A positron with kinetic energy 2.2 MeV and an electron at rest annihilate each other. Calculate the average energy of each of the two gamma photons produced as a result of this annihilation. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................

(ii) Sketch, on the diagram above, the path of the pions from the point of entry into the field to the point of exit from the field. (iii) If the magnetic field were increased, how would this affect the paths of the particles? ............................................................................................................... ............................................................................................................... ............................................................................................................... (7) (Total 9 marks) Q6. The circuit diagram shows a light-emitting diode connected in series with a resistor R and a 3.0 V battery of negligible internal resistance. The potential difference across the terminals of the diode is 2.0 V and the current through it is 10 mA. The diode emits photons of wavelength 635 nm. (a) Calculate the resistance of R. ........................................................................................................................ ........................................................................................................................

(b) Calculate the electrical power supplied to the diode. ........................................................................................................................ ........................................................................................................................ (c) Calculate the energy of a photon of wavelength 635 nm. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ (d) Estimate the number of photons emitted per second by the diode. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ (e) State an assumption you made in your estimation in part (d). ........................................................................................................................ ........................................................................................................................ (Total 8 marks) Q7. An atom of argon is ionised by the removal of two orbiting electrons. (a) How many protons and neutrons are there in this ion? ....................................... protons ...................................... neutrons

(ii) State what roles exchange particles can play in an interaction. ............................................................................................................. ............................................................................................................. ............................................................................................................. (4) (b) From the following list of particles, p e+^ μ –^ π^0 identify all the examples of (i) hadrons, ............................................................................................. (ii) leptons, …........................................................................................... (iii) antiparticles, ....................................................................................... (iv) charged particles. ............................................................................... (4) (Total 8 marks) Q9. Under certain conditions a γ photon may be converted into an electron and a positron. (a) What is this process called? ...................................................................................................................... (1) (b) (i) Explain why there is a minimum energy of the γ photon for this conversion to take place and what happens when a γ photon has slightly more energy than this value. ............................................................................................................. ............................................................................................................. ............................................................................................................. .............................................................................................................

(ii) Using values from the data sheet calculate this minimum energy in MeV. ............................................................................................................. ............................................................................................................. (3) (c) Under suitable conditions, a γ photon may be converted into two other particles rather than an electron and positron. Give an example of the two other particles it could create. ...................................................................................................................... (1) (Total 5 marks) Q10. (a) An unstable nucleus, , can decay by emitting a β–^ particle. (i) What part of the atom is the same as a β–^ particle? ............................................................................................................. (1) (ii) State the changes, if any, in A and Z when X decays. change in A ......................................................................................... change in Z. ......................................................................................... (2) (b) In the process of β–^ decay an anti-neutrino is also released. (i) Give an equation for this decay.

(1) (iii) What is the quark structure of a meson? ............................................................................................................. (1) (b) State one similarity and one difference between a particle and its antiparticle. similarity ....................................................................................................... ...................................................................................................................... difference ...................................................................................................... ....................................................................................................................... (2) (c) Complete the table below which lists properties of the antiproton. charge / C baryon number quark structure antiproton (2) (d) The K–^ is an example of a meson with strangeness –1. The K–^ decays in the following way: K–^ → μ –^ + (i) State, with a reason, what interaction is responsible for this decay. ............................................................................................................. ............................................................................................................. ............................................................................................................. ............................................................................................................. (2)

(ii) State two properties, other than energy and momentum, that are conserved in this decay. ............................................................................................................. ............................................................................................................. ............................................................................................................. ............................................................................................................. (2) (Total 11 marks) Q12. (a) Pair production can occur when a photon interacts with matter. Explain the process of pair production. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ (2) (b) Explain why pair production cannot take place if the frequency of the photon is below a certain value. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ (3)

(iii) Give one property of an antiparticle that is the same for its corresponding particle and one property that is different. Same .................................................................................................... ............................................................................................................... Different ................................................................................................ ............................................................................................................... (2) (Total 11 marks) Q14. (a) Complete the table to show the four fundamental forces and their corresponding exchange particles. fundamental force corresponding exchange particle strong nuclear gluon electromagnetic W+W−^ Z^0 gravitational graviton (2) (b) Name the physical quantity that a particle must have for the electromagnetic force to act on it. ........................................................................................................................ (1) (c) Name the particle believed to be responsible for mass. ........................................................................................................................ (1)

(Total 4 marks) Q15. (a) The positive kaon, K+, has a strangeness of +1. (i) What is the quark structure of the K+? ............................................................................................................... (1) (ii) What is the baryon number of the K+? ............................................................................................................... (1) (iii) What is the antiparticle of the K+? ............................................................................................................... (1) (b) The K+^ may decay into a neutrino and an antimuon in the following way. K+^ → v μ + μ+ (i) Complete the table using ticks and crosses as indicated in the first row. Classification K+^ v μ μ+ lepton × ✓ ✓ charged particle hadron meson (3) (ii) In this decay, charge, energy and momentum are conserved.

M1. (a) Be + α C + n (condone N; any other symbol must be defined as a neutron) B (Condone other symbols if Z and A correct) B 2 (b) (i) udd (1 up quarks and 2 down quarks) B 1 (ii) A meson has only two quarks (whereas a baryon has three) B 1 [4] M2. (a) electron B 1 (b) they annihilate (condone disappear/destroy or eliminate each other) B forming (two) gamma ray(s)/radiation or photon(s) (i.e. condone singular) NOT just energy B 2 [3]

M3. (a) any neutrino C electron anti neutrino A 2 (b) 0 → 1 + (-1) + 0 B 1 → 1 + 0 + 0 B 0 → 0 + 1 + (-1) B 3 [5] M4. (a) (i) including, for example: positron is an antimatter particle; proton is a matter particle () positron is a lepton; proton is a hadron () positron has a smaller rest mass than a proton () positron is not composed of other particles; proton is made up of quarks () (*) any two [1] [1] (ii) proton path has greater radius of curvature than positron (1) (iii) radius of curvature r = and υ, B and e are constants (1) therefore r proportional to m (1) mass of proton is (much) greater than mass of positron (at same speed) (1) 5