Discovery of Radiation and Radioactivity
The History of the Discovery of Radiation and Radioactivity
Introduction: Radiation can be defined as the propagation of energy through matter or space. It can be in the form of electromagnetic waves or energetic particles.
Ionizing radiation has the ability to knock an electron from an atom, i.e. to ionize. Examples of ionizing radiation include: • alpha particles • beta particles • neutrons • gamma rays • x-rays Non-ionizing radiation does not have enough energy to ionize atoms in the material it interacts with. Examples of non-ionizing radiation include: • microwaves • visible light • radio waves • TV waves • Ultraviolet radiation (except for the very shortest wavelengths) The earth has been radioactive ever since its formation into a solid mass over 4½ billion years ago. However, we have only known about radiation and radioactivity for just over one hundred years. [One hundred and four years and 10 months to be exact.] You are probably familiar with the radiation warning sign, the “trefoil”. See http://www.orau.com/ptp/articlesstories/radwarnsymbstory.htm for a history of the symbol.
A Brief History of the Discovery of Radiation and Radioactivity The History of the Discovery of Radiation and Radioactivity
1
1895: The Discovery of the X-ray Radiation was discovered by Wilhelm Conrad Roentgen on November 8, 1895. http://www.orcbs.msu.edu/radiation/radhistory/wilhelmrontgen.html Roentgen, like many other physicists at that time, had been experimenting in his laboratory with the discharge of electricity in “vacuum tubes”. The glass tubes were evacuated (and made airtight using Bank of England sealing wax) and had metal plates sealed at the ends. The metal plates could be connected to a battery or an induction coil. This flow of electricity was necessary in order for the tube to glow. The glow emerged from the negative plate (the cathode) and disappeared into the positive plate (the anode). If a circular anode was sealed into the middle of the tube,
Introduction: Radiation can be defined as the propagation of energy through matter or space. It can be in the form of electromagnetic waves or energetic particles.
Ionizing radiation has the ability to knock an electron from an atom, i.e. to ionize. Examples of ionizing radiation include: • alpha particles • beta particles • neutrons • gamma rays • x-rays Non-ionizing radiation does not have enough energy to ionize atoms in the material it interacts with. Examples of non-ionizing radiation include: • microwaves • visible light • radio waves • TV waves • Ultraviolet radiation (except for the very shortest wavelengths) The earth has been radioactive ever since its formation into a solid mass over 4½ billion years ago. However, we have only known about radiation and radioactivity for just over one hundred years. [One hundred and four years and 10 months to be exact.] You are probably familiar with the radiation warning sign, the “trefoil”. See http://www.orau.com/ptp/articlesstories/radwarnsymbstory.htm for a history of the symbol.
A Brief History of the Discovery of Radiation and Radioactivity The History of the Discovery of Radiation and Radioactivity
1
1895: The Discovery of the X-ray Radiation was discovered by Wilhelm Conrad Roentgen on November 8, 1895. http://www.orcbs.msu.edu/radiation/radhistory/wilhelmrontgen.html Roentgen, like many other physicists at that time, had been experimenting in his laboratory with the discharge of electricity in “vacuum tubes”. The glass tubes were evacuated (and made airtight using Bank of England sealing wax) and had metal plates sealed at the ends. The metal plates could be connected to a battery or an induction coil. This flow of electricity was necessary in order for the tube to glow. The glow emerged from the negative plate (the cathode) and disappeared into the positive plate (the anode). If a circular anode was sealed into the middle of the tube,