EduNinja
[Maximum number: 1]

This question is about objects in the universe.

(a)

State how

[ 1 ]
(i)

it is known that main sequence stars are made predominantly of hydrogen.

[ 1 ]
[Maximum number: 1]

What is the best estimate for the diameter of a helium nucleus?

A

10−21 m10^{-21} \mathrm{~m}

B

10−18 m10^{-18} \mathrm{~m}

C

10−15 m10^{-15} \mathrm{~m}

D

10−10 m10^{-10} \mathrm{~m}

[Maximum number: 1]

The ratio of the diameter of an atom to the diameter of its nucleus is:

A

10110^{1}

B

10310^{3}

C

10510^{5}

D

10710^{7}

[Maximum number: 4]

The diagram shows the three lowest energy levels of the hydrogen atom.

The energy of each level is indicated.

Question image
(a)

State the number of transitions between these levels that result in the emission of photons.

[ 1 ]
(b)

Calculate the largest photon wavelength for these transitions.

[ 3 ]
[Maximum number: 4]

The diagram shows the three lowest energy levels of the hydrogen atom.

The energy of each level is indicated.

Question image
(a)

State the number of transitions between these levels that result in the emission of photons.

[ 1 ]
(b)

Calculate the largest photon wavelength for these transitions.

[ 3 ]
[Maximum number: 2]

The Feynman diagram shows electron capture.

Question image
(a)

Distinguish between hadrons and leptons.

[ 2 ]
(a)

Rutherford modelled the scattering of alpha particles by a nucleus of gold. However, when the initial alpha particle energy is greater than a certain value E0E_{0}, the fraction of alpha particles scattered at angles close to 180∘180^{\circ} does not follow Rutherford's model.

Outline

[ 3 ]
(i)

why this deviation from the model occurs, and

[ 1 ]
(ii)

how E0E_{0} can be used to estimate the nuclear radius of gold.

Gold-198 (Au-198) is a radioactive nuclide of gold. Au-198 decays into stable mercury-198 (Hg-198) with an emission of a beta particle followed by one or two gamma photons.

The half-life of Au-198 is 2.69 days.

[ 2 ]
[Maximum number: 4]

D2. This question is about quarks and interactions.
(a) Outline how interactions in particle physics are understood in terms of exchange particles.
(b) The sigma ( Σ+=uus\Sigma^{+}=\mathrm{u} \mathrm{u} \mathrm{s} ) decays into a positive pion ( π+=ud‾\pi^{+}=\mathrm{u} \overline{\mathrm{d}} ) and a neutron according to the following reaction.

∑+→n+π+\sum^{+} \rightarrow \mathrm{n}+\pi^{+}

The colour of each of the quarks in Σ+\Sigma^{+}is indicated in the diagram below.

Question image

Deduce
(i) the colour of the d‾\overline{\mathrm{d}} in π+\pi^{+}.
(ii) the electric charge of the particle represented by the dotted line.
(c) Determine whether or not strangeness is conserved in this decay.
(d) The total energy of the particle represented by the dotted line is 1.2 GeV more than what is allowed by energy conservation. Determine the time interval from the emission of the particle from the s quark to its conversion into the dd‾\mathrm{d} \overline{\mathrm{d}} pair.
(e) The pion is unstable and decays through the weak interaction into a neutrino and an anti-muon.

Draw a Feynman diagram for the decay of the pion, labelling all particles in the diagram.

(a)

A stationary isotope of 88Ra{ }_{88} \mathrm{Ra} (Radium) decays into Rn (Radon) and an alpha particle.

[ 1 ]
(i)

Identify the proton number of Rn .

The following data are available:
Atomic mass of Ra=226.02540 u
Atomic mass of Rn=222.01757 u
Mass of α=4.00260u\alpha=4.00260 \mathrm{u}

[ 1 ]
(b)

In an experiment performed by Geiger, Marsden and Rutherford to investigate the atomic structure, alpha particles were directed into a thin metal foil.

[ 4 ]
(i)

Describe two observations of this experiment.

[ 2 ]
(ii)

Outline how the experiment was interpreted.

[ 2 ]
[Maximum number: 3]

This question is about polarization.
Outline how polarization may be used in stress analysis.

This question is about atomic energy levels.

(a)

Explain how atomic spectra provide evidence for the quantization of energy in atoms.

[ 3 ]
0