Two discoveries: X-rays and Radiation
Nuclear radiation, a kind of energy more
complicated than fire or electricity, seems to combine mystery with a sense
of danger. Radiation can both heal and kill. From this website you will
learn the theories and functioning of radiation but in this section the
focus is on history. Radioactive substances have also been the cause of
mass destruction and death. In August 1945, two atomic bombs destroyed
the Japanese cities of Hiroshima and Nagasaki, killing thousands in instances.
To physicists the study of radiation quickly led to an outpour of more
questions and discoveries.
German Physicist Wilhelm Conrad Rontgen discovered a form of
energy that could pass through solid objects. He was unsure what this was
and called it X-rays, X being the symbol for unknown. Almost immediately
doctors began to use X rays to assist in seeing the insides of the body.
Scientists began to study the effects of X rays on a variety of substances.
One such experiment carried out in 1896 by Antoine Henri Becquerel
discovered a second type of new rays known as 'Becqueral rays'.
Intrigued by Roentgen's recent discovery of X rays, Becquerel looked
for X-rays in Uranium salts. But the unexpected happened, as it
has on numerous other occasions in physics: Becquerel discovered that these
salts emitted a new form of radiation. He found that the more uranium he
used the more intense the rays were and concluded that the radiation came
from Uranium.
Becquerel's Experiment
You are probably familiar with phosphorescence in the form of glow-in-the-dark
toys. You know that if you leave these toys in a dark place for a long
enough time, they will stop glowing. These materials cannot produce
light on their own, they store light from another source and emit it for
a short period after exposure. Becquerel knew that uranium salts were phosphorescent
and wondered if they were emitting X -rays.
On a day in March, Becquerel was going to carry out his experiment
to find out if X-rays were present in Uranium. Unfortunately it was cloudy
on that day and he couldn't use the sun which he needed in the experiment.
He wrapped up his equipment, including photographic plates, and put them
in his drawer. A few days later he took his equipment out again and to
his surprise he had found that the photographic plates had darkened which
meant that they had been exposed to an energy of some sort. From this Becqueral
found that uranium had been emitting rays on their own. From there he discovered
radiation.
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Becqueral's apparatus |
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