towards an analysis of errors made by university students ... - DSpace

ions produced in a volume of gas. Since these carry an electric
charge there are a number of extremely
delicate methods by which
they can be' detected. The widely used Geiger counter
consists
essentially of a wire stretched inside a cylindrical tube, so
arranged that an electric current can pass between the wire
and
the tube only when there are ions in the gas. Consequently,
when an ionizing particle passes through the tube, an electric
signal is given out. In this way the number of ionizing
particles given off by a radio-active source can be accurately
à .
counted. This is called the activity of the material.
It is
measured in a unit called the 'curie' after the discoverer of
radium. The activity of one gram of radium together with
its
decay products is equal to one curie. Every time an atom
disintegrates a beta- or alpha-ray is given off together with
a certain amount o^ gamma radiation. The activity
in curies
can tell us nothing about the dose of radiation given off by
the radio-active material, since the curie measures only the
number of ionizing particles emitted, independent of their range
or energy.
(From chapter I of ATOMIC RADIATION AND LIFE, by
Peter
Alexander.)
1.2.2. Texts translated by the Nursing Group
TIN - Text number 1 - Nursing
THE NERVOUS
SYSTEM
We have a number of special
nerves which pick up