2 Quarks and leptons
Exam-style questions
AQA Physics
1
Sub-atomic particles can either be hadrons or leptons.
a State one difference between these two groups of particles.
(1 mark)
b Give an example of a non-strange hadron and an example of a lepton.
hadron
lepton
(2 marks)
c
Hadrons can be further divided into two groups. Name these two groups and
state a difference between them.
(3 marks)
From AQA Physics A PHYA1 Particles, Quantum Phenomena and Electricity
January 2011 (Question 1)
© Oxford University Press 2015
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
1
2 Quarks and leptons
Exam-style questions
AQA Physics
2
a
The table gives information about some fundamental particles.
Complete the table by filling in the missing information.
Particle
Quark
structure
Charge
uud
Sigma+
uus
Strangeness
Baryon
number
0
+1
ud
0
0
(7 marks)
b Each of the particles in the table in part a has an antiparticle.
i Give one example of a baryon particle and its corresponding antiparticle.
particle
antiparticle
(1 mark)
ii
State the quark structure of an antibaryon.
(1 mark)
iii Give one property of an antiparticle that is the same for its corresponding
particle and one property that is different.
Same
Different
(2 marks)
From AQA Physics A PHYA1 Particles, Quantum Phenomena and Electricity
January 2012 (Question 1)
© Oxford University Press 2015
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
2
2 Quarks and leptons
Exam-style questions
AQA Physics
3
a
The Σ+ particle is a baryon with strangeness –1.
i How many quarks does the Σ+ particle contain?
ii
answer
(1 mark)
answer
(1 mark)
How many of the quarks are strange?
b The Σ decays in the following reaction
Σ+ → π+ + n
+
i
State two quantities that are conserved in this reaction.
(2 marks)
ii
State a quantity that is not conserved in this reaction.
(1 mark)
iii What interaction is responsible for this reaction?
(1 mark)
iv Into what particle will the neutron formed in this reaction eventually
decay?
(1 mark)
From AQA Physics PHYA1 Particles, Quantum Phenomena and Electricity June
2009 (Question 3)
c
Mesons that contain a strange (or antistrange) quark are known as
K-mesons or kaons. Mesons are a sub-group of a larger group of particles.
i State the name of this larger group of particles.
(1 mark)
© Oxford University Press 2015
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
3
2 Quarks and leptons
Exam-style questions
AQA Physics
ii
Determine the charge on a kaon with a quark structure of us .
(1 mark)
d A proposed decay for this kaon is
us ® m + + vm
i
Apply the law of conservation of strangeness to the proposed decay.
(1 mark)
ii
Comment on whether or not this decay is possible.
(1 mark)
From AQA Physics B PHYB1 Harmony and Structure in the Universe January 2013
(Question 4)
© Oxford University Press 2015
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
4
2 Quarks and leptons
Exam-style questions
AQA Physics
4
a
The K– meson has strangeness –1.
i State the quark composition of a meson.
(1 mark)
ii
State the baryon number of the K– meson.
(1 mark)
iii What is the quark composition of the K– meson?
(1 mark)
b i
Complete this equation for the decay of a K – meson.
K– →
+
+
(2 marks)
From AQA Physics A PHYA1 Particles, Quantum Phenomena and Electricity June
2012 (Question 1)
5
a
i
Name two baryons.
(1 mark)
ii
State the quark structure of the pion π+.
(1 mark)
b i
The K+ kaon is a strange particle. Give one characteristic of a strange
particle that makes it different from a particle that is not strange.
(1 mark)
ii
One of the following equations represents a possible decay of the K + kaon.
K+ → π+ + π 0
K+ → μ + + v μ
© Oxford University Press 2015
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
5
2 Quarks and leptons
Exam-style questions
AQA Physics
State, with a reason, which one of these decays is not possible.
(2 marks)
c
Another strange particle, X, decays in the following way:
X → π– +p
i
State what interaction is involved in this decay.
(1 mark)
ii
Show that X must be a neutral particle.
(1 mark)
iii Deduce whether X is a meson, baryon, or lepton, explaining how you
arrive at your answer.
(2 marks)
iv Which particle in this interaction is the most stable?
(1 mark)
From AQA Physics A PHYA1 Particles, Quantum Phenomena and Electricity June
2011 (Question 1)
© Oxford University Press 2015
www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
6