George Robinson, age 13, of Bessemer, Ala., for his question:
CAN YOU EXPLAIN OPTICS?
Optics is the branch of physics that is concerned with the properties of light. It describes how light is produced, how it is transmitted and how it can be measured and detected. Optics also includes the study of visible light and of infrared and ultraviolet rays, both of which are invisible.
Binoculars, cameras, magnifiers, microscopes, projectors and telescopes are among the instruments that operate according to the principles of optics. All these instruments have optical devices, such as lenses and mirrors, which transmit and control light.
Light is detected and measured with instruments called light meters.
Scientists have used the principles of optics to increase the number of ways that light can be employed. As an example, they can transmit light along a twisted or curved path by sending the light through a filament called an optical fiber. Scientists also use a device called a laser as an important and powerful light source.
There are two major branches of optics: physical optics and geometrical optics. Physical optics deals with the nature and behavior of light. Geometrical optics is concerned with optical instruments and what happens when light strikes them.
The development of optics started chiefly during~the 1600s. A famous Italian scientist named Galileo built telescopes to observe the planets and the stars. Then in England a scientist named Isaac Newton experimented with lenses and used a prism to break sunlight into its colors. And in Holland a physicist named Christian Huygens studied polarization and proposed a wave theory of light.
The principles of optics describe what light is and how it behaves. To study visible light, scientists use a prism or wedge of glass that produces a band of colors called the visible spectrum. Scientists analyze this and other strata with an instrument called a spectroscope.
Several reactions may occur when light strikes the surface of an object. Diffraction, interference, reflection and refraction and basic principles that describe what may happen.
Other principles include the chemical effects of light, dispersion, the photoelectric effect and polarization.
During the 1800s, two physicists did much to confirm Huygens, theory. In England, a physicist named Thomas Young formulated the principle of the interference of light. And in France, a physicist named Augustin Fresnel developed a mathematical formula that supported this principle. Most scientists accepted the work of Young and Fresnel as proof of Huygens' theory.
Later in the 1800s accurate measurements of the speed of light were made by the French scientists Armand Fiuzeau and Jean Foucault. At about the same time, two German scientists, Robert Bunsel and Gustav Kerchoff, showed that atoms of chemical elements produced the color bands of the spectrum.
During the late 1800e and the 1900s, such scientists as Albert Michelson of the United States, Fritz Zernike of The Netherlands and Dennis Gabor of England received the Nobel prize for physics for their work in optics.