Exam-style Questions: Particle Classification and Interactions

 

 

 

  1. a) Write down the charges of the up, down and strange quarks.

    b) Show how a neutron and a proton carrying the correct charges can be formed from different combinations of 3 up and down quarks.

    (Marks available: 2)

    Answer

     

    Answer outline and marking scheme for question: 1

    a) up = +2/3e, down = -1/3e and strange = -1/3e

    (1 mark)

    b) proton has charge +1e so needs two up and one down quark (2/3+/2/3-1/3 = +1)

    (1 mark)

    (Marks available: 2)

  2. How many up quarks does an alpha particle contain?

    (Marks available: 3)

    Answer

     

    Answer outline and marking scheme for question: 2

    Alpha particle is made up of 2 protons and 2 neutrons

    (1 mark)

    Protons have 1 up quark and neutrons 2 up quarks

    (1 mark)

    So total up quarks = 5

    (1 mark)

    (Marks available: 3)

  3. Within the nucleus positive protons in are very close together. A student suggests that as a result no nuclei can be stable due to the electromagnetic repulsion between them. Suggest an interaction which could be responsible for holding the nucleus together, give its properties and explain your reasoning.

    (Marks available: 5)

    Answer

     

    Answer outline and marking scheme for question: 3

    Strong interaction

    (1 mark)

    Properties: Caused by the exchange of mesons

    (1 mark)

    Range = 10-15m

    (1 mark)

    Strong interaction is stronger than electromagnetic interaction

    (1 mark)

    over short ranges as found in the nucleus

    (1 mark)

    (Marks available: 5)

  4. The Rutherford scattering experiment is an example of the use of radioactive particles.

    a) What type of radiation was used in the experiment?

    b) What physical property caused the scattering?

    c) The particles in this experiment are unsuitable for probing the structure of the nucleus itself. Suggest a different particle that could be used stating the physical principle that causes the scattering in this case.

    d) Give another use of radioactive particles and state the source of radiation involved.

    (Marks available: 6)

    Answer

     

    Answer outline and marking scheme for question: 4

    a) Alpha radiation

    b) Electrostatic repulsion

    c) Electrons

    (1 mark)

    Diffraction

    (1 mark)

    d) e.g. radioactive dating

    (1 mark)

    carbon 14

    (1 mark)

    or medical tracing

    (1 mark)

    technetium 99m

    (1 mark)

    (Marks available: 6)