AQA A Level Physics

Topic Questions

8.1 Alpha, Beta & Gamma Radiation

11 mark

Radiation can be both useful and dangerous. The diagram below shows some contributors to background radiation.

q1-8-1-mcq-alpha-beta-gamma-radiation

Which of the following is not a major contributor to background radiation?

  • Cosmic rays

  • Isotopes in food & drink

  • Fallout from testing nuclear devices

  • Buildings

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21 mark

β particles are emitted from a radioactive source.

Which of the following statements is correct for these particles?

  • They are absorbed by aluminium

  • They are absorbed by paper

  • They will not be deflected by a magnetic field

  • They do not damage human tissue

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31 mark

In the Rutherford scattering experiment most  particles passed through the foil undeflected.

What is a correct deduction from this result?

  • The charge of the atom is neutral

  • The nucleus has a positive charge

  • Most of the mass of an atom is within the nucleus

  • The diameter of the nucleus is much less than the diameter of the atom

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41 mark

Which expression correctly describes the inverse square law for radiation?

  • I = kx

  • Ik over x

  • I = kx2

  • Ik over x squared

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51 mark

Which of the following statements is what the Rutherford scattering experiment has led to?

  • the quark model of hadrons

  • the discovery of the electron

  • evidence for wave–particle duality

  • the discovery of the nucleus

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11 mark

In an α–particle scattering experiment, a student set up the apparatus, as shown in the diagram below, to determine the number n of α–particles incident per unit time on a detector held at various angles θ.

q12-1-8-1-mcq-alpha-beta-gamma-radiation

Which of the following graphs best represents the variation of n with θ?

q12-2-8-1-mcq-alpha-beta-gamma-radiation

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21 mark

A student detects the counts from a radioactive source using a G–M radiation detector as shown in the diagram. The student places the source at different distances, d, and measures the count rate.

q13-8-1-mcq-alpha-beta-gamma-radiation

When the detector is placed 0.50 m the source, it receives a mean count rate of 1750 counts per minute. The mean background radiation is measured as 70 counts per minute.

The count rate should not exceed 5000 counts per minute.

What is the smallest distance of d the source can be placed at to avoid exceeding the limit?

  • 4 cm

  • 6 cm

  • 9 cm

  • 29 cm

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31 mark

A γ ray detector with a cross–sectional area of 5.0 × 10–3 m2 is placed 0.20 m from a source.

A corrected count rate of 1.2 counts s–1 is recorded. The γ ray detector detects 1 in 100 of the γ photons incident on the facing surface of the detector.

How many photons are produced by the source every second?

Assume the source emits γ rays uniformly in all directions.

  • 1.2 photons s−1

  • 3000 photons s−1

  • 12000 photons s−1

  • 2400 photons s−1

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41 mark

Polythene film is made by extruding polythene and drawing it into a long sheet which is wound onto a roll, as shown in the diagram below.q15-8-1-mcq-alpha-beta-gamma-radiation

The manufacturer has to carefully choose a radioactive isotope which will effectively remove any electrostatic charge that has built up on the film. The manufacturer also has to consider the point X, Y or Z at which the radioactive isotope should be placed along the assembly line.

Which point should the radioactive be placed at, and which type of radiation should the manufacturer choose to remove excess electrostatic charge?

 

Point

Type of radiation

A

B

C

D

X

X

Y

Z

alpha

gamma

beta

alpha

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51 mark

A scientist is working with a sample of potassium–42 which initially has an activity of 2.0 × 107 decays per second. When potassium–42 decays it emits β particles and gamma rays.

To determine the dose received by a scientist working with the source the number of gamma ray photons incident on each cm2 of the body has to be known.

One in every five of the decaying nuclei produces a gamma ray photon. The scientist is initially working 1.50 m from the source with no shielding.

The scientist returns 12 hours later to find the dose at the same distance has reduced to 7gamma rays per cm2 per second.

At what distance from the source could the scientist now work and receive the same dose of photons per second per cm2 as 12 hours earlier?

  • 1.30 m

  • 1.20 m

  • 1.10 m

  • 1.00 m

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11 mark

A series of radioactive decays starts with an isotope of thorium, nucleon (mass) number 230, proton (atomic) number 90.

Which line in the table shows the nucleon number and proton number of the isotope after the emission of 4 α particles and 2 βparticles?

 

Nucleon number

Proton number

A

B

C

D

214

222

222

214

84

84

82

82

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21 mark

In an experiment to investigate the structure of the atom, alpha particles accelerated to the same speed were fired at gold nuclei.

The diagrams below represent possible paths taken by two alpha particles at two different times and the maximum forces acting on the alpha particles as a result of the electrostatic forces between a gold nucleus, labelled Au, and the alpha particles.

Which diagram best represents the possible paths of the alpha particles and the forces acting on them?

q7-8-1-mcq-alpha-beta-gamma-radiation

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31 mark

A Geiger counter is placed near a radioactive source and different materials are placed between the source and the Geiger counter.

The results of the tests are shown in the table.

Material

Count rate of Geiger counter / s–1

None

500

Paper

350

Aluminium foil

350

Thick steel

150

What is the radiation emitted by the source?

A

α only

B

α and γ

C

α and β

D

β and γ

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41 mark

A detector and counter are used to measure the count rate from a gamma source.

Which graph shows how the corrected count rate will vary with distance, d, between the source and detector?

ma9-8-1-mcq-alpha-beta-gamma-radiation

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51 mark

The diagram below shows an arrangement used to maintain a constant thickness of sheet paper or steel as it is being rolled. A radioactive source and detector are used to monitor the thickness.

q10-8-1-mcq-alpha-beta-gamma-radiation

Alpha, beta or gamma sources could be selected for use in such an arrangement.

Which source would be the most suitable in each case?

 

Paper

Steel

A

B

C

D

alpha

beta

alpha

beta

beta

alpha

gamma

gamma

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61 mark

Which type of radiation is the most suitable for the following purposes?

 

In a smoke detector

As a medical tracer

Monitoring thickness of aluminium foil

Testing for cracks in pipes

A

B

C

D

alpha

beta

alpha

alpha

beta

gamma

beta

gamma

gamma

gamma

beta

beta

alpha

gamma

alpha

gamma

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