Uses of radioisotopes Flashcards

1
Q

Background radiation is due to:

A
  • Radioactive substances present in rock (especially granite) and soil.
  • Cosmic rays from Space.
  • Man-made sources include radioactive waste from industry and hospitals.
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2
Q

When using a tracer to locate a leak in an underground pipe:

A
  • A very small amount of gamma emitter is put into the pipe.
  • A detector is passed along the ground above the path of the pipe.
  • An increase in activity is detected in the region of the leak and little or no activity is detected after this point.
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3
Q

Why are gamma sources used as tracers?

A

Gamma sources are used as tracers because the radiation is able to penetrate to the surface.

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4
Q

How does a smoke detector work?

A
  • A smoke detector contains an isotope which emits alpha particles.
  • Without smoke, the alpha particles ionise the the air to create a tiny current that can be detected by the circuit in the smoke alarm.
  • With smoke, the alpha particles are partially blocked so there is less ionisation of the air. The resulting change in current is detected and the alarm sounds.
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5
Q

Some rock types contain traces of uranium, a radioactive material.

A
  • Some rocks such as granite contain traces of uranium, a radioactive material.
  • The uranium isotopes present in the rocks go through a series of decays, eventually forming a stable isotope of lead.
  • The proportion of lead increases as time increases. If there are equal amounts of 235U and 206Pb, the rock is 4500 million years old.
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6
Q

What is carbon-14?

A

Carbon-14 is a radioactive isotope of carbon that is present in all living organisms. By measuring the amount of carbon-14 present in an archaeological find, its approximate age can be found.

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7
Q

Carbon dating can only be used on objects that were once alive.

A
  • When an object dies, no carbon-14 is produced.
  • As the carbon-14 decays, the activity of the sample decreases.
  • The ratio of current activity from living matter to the sample activity provides a reasonably accurate date.
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