Question 1a

Marks: 3

The Rutherford-Geiger-Marsden Experiment provided evidence for the structure of the atom. The set up consisted of alpha particles being fired at a thin gold foil, with a detector to detect deflected particles.

The diagram shows some of the potential paths taken by the alpha particles.

7-3-q1a-question-diagram-1-sl-sq-easy-phy

(a)

Draw lines to connect the correct statements for each path of the alpha particle.

7-3-q1a-question-diagram-2-sl-sq-easy-phy

[3]

Key Concepts

The Rutherford-Geiger-Marsden Experiment

Question 1b

Marks: 5

Since Rutherford's discovery, further discoveries about the nature of matter have been made.

(b)

Complete the following sentences with appropriate words or phrases:

The nucleus is made of ________ and ________, and these themselves are made of the fundamental particles known as ________. Any particle made of these is known as a ________. Another example of a fundamental particle is the ________.

[5]

Key Concepts

Protons & Neutrons
Quarks & Leptons

Question 1c

Marks: 6

One type of hadron is the K+ meson, which has a strangeness of +1.

(c)

(i)

State the quark composition of a meson

[1]

(ii)

State the baryon number of a K+ meson

[1]

(iii)

Show that the quark composition of a K+ meson is

u \bar{s}

[4]

Key Concepts

Quarks & Leptons

Question 1d

Marks: 3

Electrons are an example of another type of fundamental particle called a lepton.

(d)

(i)

State the charge on a muon.

[1]

(ii)

State the mass of the electron neutrino.

[1]

(iii)

State the fundamental force which leptons do not interact with, but quarks do.

[1]

Key Concepts

Quarks & Leptons

Question 2a

Marks: 5

The following particles are available:

$p \bar{n} μ^{+} e^{+} γ$

(a)

Identify all examples of:

(i)

Hadrons.

[1]

(ii)

Leptons.

[1]

(iii)

Antiparticles.

[1]

(iv)

Charged particles.

[1]

(v)

Exchange particles.

[1]

Key Concepts

Quarks & Leptons
Hadrons, Baryons & Mesons

Question 2b

Marks: 2

Quarks can combine to give various baryons and mesons. The proton and neutron are the baryons which subsequently make up the nucleus.

(b)

State the quark composition of:

(i)

A proton.

[1]

(ii)

A neutron.

[1]

Key Concepts

Protons & Neutrons

Question 2c

Marks: 2

The proton has a charge of +1e.

(c)

Explain why the proton has this charge by referring to the charge of its constituent quarks.

[2]

Key Concepts

Protons & Neutrons

Question 2d

Marks: 6

Protons and neutrons are both examples of baryons. An electron is an example of a lepton

(d)

Complete the table below with the correct charge, baryon and lepton numbers for each particle.

	Charge	Baryon number	Lepton number
Proton, $p$	+1	1
Anti-Neutron, $\bar{n}$			0
Pion minus, $π^{-}$	−1		0
Photon, $γ$	0	0
Up quark, $u$	$+ \frac{2}{3}$		0
Electron, $e$		0

[6]

Key Concepts

Hadrons, Baryons & Mesons

Question 3a

Marks: 2

The four fundamental forces are mediated through exchange particles.

(a)

Define the phrase 'exchange particle'.

[2]

Key Concepts

Exchange Particles

Question 3b

Marks: 4

(b)

Draw lines to match the force with the correct exchange particle:

[4]

Key Concepts

Exchange Particles

Question 3c

Marks: 3

(c)

Arrange the four fundamental forces in the boxes below the arrow in order of strongest to weakest.

[3]

Key Concepts

Fundamental Forces

Question 3d

Marks: 1

Feynman diagrams represent particle interactions in the form of a diagram.

The following is a Feynman diagram showing beta−minus decay, with the exchange particle missing.

7-3-q3d-question-sl-sq-easy-phy

(d)

Label the correct exchange particle on the diagram.

[1]

Key Concepts

Feynman Diagrams
Fundamental Forces

Question 4a

Marks: 2

(a)

State what is meant by the standard model of particle physics.

[2]

Key Concepts

The Standard Model of Particle Physics

Question 4b

Marks: 3

The standard model describes the fundamental particles that make up other sub-atomic particles.

One method of representing the standard model is as shown in the diagram below.

7-3-q4b-question-sl-sq-easy-phy

(b)

Complete the missing information in the boxes in the diagram.

[3]

Key Concepts

The Standard Model of Particle Physics

Question 4c

Marks: 3

Another more detailed way of showing the standard model is shown below, where the different fundamental particles are arranged on cards:

7-3-q4c-question-sl-sq-easy-phy

(c)

By writing a letter in the correct box, identify:

(i)

Quarks, with the letter Q

[1]

(ii)

Leptons, with the letter L

[1]

(iii)

Gauge bosons, with the letter B

[1]

Key Concepts

The Standard Model of Particle Physics

Question 4d

Marks: 1

The final particle on the standard model diagram in part (b) is the Higgs boson. It was predicted in 1964 and confirmed in 2012.

(d)

State what the Higgs boson is responsible for.

[1]

Key Concepts

The Higgs Boson

Question 5a

Marks: 2

The following Feynman diagram shows a particle interaction.

7-3-q5a-question-sl-sq-easy-phy

(a)

Label the axes of the Feynman diagram.

[2]

Key Concepts

Feynman Diagrams

Question 5b

Marks: 2

(b)

State:

(i)

The exchange particle in the interaction shown in part (a).

[1]

(ii)

The fundamental force represented by this exchange particle.

[1]

Key Concepts

Exchange Particles
Fundamental Forces

Question 5c

Marks: 6

The Feynman diagram in part (a) represents part of the particle interaction

$π^{-} + p \to K^{0} + Λ^{0}$

The composition of each particle in terms of quarks is:

$π^{-} = d \bar{u}$
$p = u u d$
$K^{0} = d \bar{s}$
$Λ^{0} = u d s$

(c)

(i)

Identify the two particles in this interaction which contain a strange or anti-strange quark .

[2]

(ii)

By considering the strangeness of each of the particles, show that strangeness is conserved in this interaction.

[3]

(iii)

State the interaction which does not conserve strangeness.

[1]

Key Concepts

Particle Conservation Laws
Comparing Fundamental Forces

Question 5d

Marks: 5

Quarks can only exist within hadrons, this is known as quark confinement.

(d)

Complete the gaps in the sentences below to describe confinement:

There are two types of hadron, ________ and ________. Quarks cannot be ________ but must be in pairs or triplets. Quarks are kept in place by ________. If an attempt is made to separate quarks, more ________ are produced using the energy required to separate them.

[5]

Key Concepts

Confinement

DP IB Physics: HL

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