Electromagnetic Spectrum Flashcards
These rays are the highest energy of electromagnetic radiation. They were discovered in 1900 by Paul Willard, who observed them being emitted from radioactive radium. This radiation has high penetrating power and may be blocked by lead or significantly thick concrete.
Gamma Rays
These rays were identified in 1895 by Wilhelm Röntgen, who named them. In respect to the German physicist, these rays are also called Röntgen waves. Röntgen’s discovery was deemed so significant , that he was awarded the first Nobel Prize in Physics in 1901 for the discovery. Most people are familiar with these through their medical use to check for broken bones, since they penetrate soft tissues easily, but have difficulty passing through dense tissue like bone. Interestingly, it was Nikola Tesla who first noticed that this radiation could expose film, producing what Tesla called “shadowgraphs.”
X-rays
This radiation was first discovered in 1801 by Johann Ritter, who noticed that invisible rays beyond violet light were able to induce chemical reactions involving silver chloride. We experience most of this radiation from sunlight, and it’s responsible for both the tanning of skin and sunburns. The short wavelength of this radiation is known to damage DNA, which is why extended exposure to sunlight without protection increases the risk of skin cancer.
Ultraviolet Radiation
This is the only form of EMR that can be perceived by the human eye. Isaac Newton first discovered that white light passing through a glass prism caused it to split into the seven basic colors of light, in a process called dispersion. The colors of this spectrum are in order form shortest to longest wavelength: violet, indigo, blue green, yellow, orange, and red.
Visible Light
This type of radiation exists just beyond the red portion of the visible spectrum. Astronomer William Herschel (1800) discovered that placing a thermometer just past the red band of dispersed visible light passing through a prism, showed an invisible source of heat. Today, infrared radiation is also known as “thermal radiation.”
Infrared Radiation
These are named because they were discovered after radio waves and were found to have shorter wavelengths than radio waves. These have many uses including uses in communication, astronomy, meteorology, wireless signal transmission, and in microwaves.
Microwaves
These waves have the longest wavelengths of all EMR, with values ranging from 1 mm to 100km. Heinrich Hertz(1887) generated radio waves, which were first predicted by James Clerk Maxwell, in his laboratory. In nature theses waves are generated whenever a charged particle is accelerated. The large wavelength of these waves allow these waves to be diffracted, or bent around objects. This makes these waves especially useful in communications on Earth.
Radio Waves
