5.2.1. Detection of radioactivity
A subsection of Physics, 5054, through 5. Nuclear physics
Listing 10 of 53 questions
A radioactive source is placed 3 cm from a Geiger-Müller tube in air. The average count rate is 742 counts / minute. source Geiger-Müller tube counter Then, in three experiments, measurements are taken with sheets of different materials placed between the source and the tube. The results are recorded in the table. material of sheet between source and tube thin card aluminium foil thick lead average count rate / counts per minute Which types of radiation does the source emit?
5054_s05_qp_1
MCQ
2005
Paper 1, Variant 0
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To find out whether a radioactive source emits alpha-particles, beta-particles or gamma-rays, the source is placed in front of a radiation detector, as shown in . detector radioactive source absorbing materials Different absorbing materials are placed between the source and the detector. The detector measures the number of counts per minute. State what is meant by an alpha-particle, a gamma-ray. Suggest why, in this experiment, 1. the distance between the source and the detector is only a few centimetres, 2. the half-life of the radioactive source is longer than a few minutes. State one precaution taken when using a radioactive source. shows the results obtained. source present material between source and detector counts per minute no none yes none yes thin paper yes 5 mm aluminium Using information from , state and explain whether the source emits alpha-particles, beta-particles, gamma-rays. There is a count recorded even when no source is present. This is caused by background radiation. State two sources of background radiation. 1. 2. Describe one effect on the human body of a very high level of radiation.
5054_s12_qp_22
THEORY
2012
Paper 2, Variant 2
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11 The nucleus of an atom of carbon-14 is represented as 14 6 C. Describe the structure of an atom of carbon-14. Carbon has several isotopes. Describe, in terms of the particles within the nucleus, how isotopes are 1. different from one another, 2. the same as one another. Carbon-14 decays by beta emission to a stable isotope of nitrogen. Carbon-14 has a half-life of 5700 years and is used to find the age of objects by carbon dating. A pure sample of carbon-14 initially contains 8.0 × 1020 atoms. Calculate the number of atoms of carbon and of nitrogen present in the sample after 11 400 years. number of atoms of carbon = number of atoms of nitrogen = Explain why carbon-14 is not used to find the age of a piece of coal that has been in the ground for millions of years. A teacher sets up the apparatus shown in . detector lead 6 mm radioactive source emitting beta-particles counter The teacher also has available a number of sheets of aluminium, each of which is 1 mm thick. Describe how the apparatus and the sheets are used to demonstrate that beta- particles are stopped by 5 mm of aluminium. In your account, make clear how the background count is measured and used. Suggest why the lead in is placed around the radioactive source during the demonstration. The radioactive source in is changed for one that emits gamma-rays. Describe why the apparatus cannot be used to find the thickness of aluminium needed to stop gamma-rays.
5054_s13_qp_21
THEORY
2013
Paper 2, Variant 1
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Questions Discovered
53