– Every point along the front of a wave is treated as many separate sources of tiny wavelets that move at the speed of the wave.- Christiaan Huygens suggested that every point along the front of a wave be treated as many separate sources of tiny “wavelets” that themselves move at the speed of the wave.
You are watching: Which color of light, red or blue, travels faster in crown glass?
– It is important to see how light moves from one medium to another and to predict the bending that occurs in Snell”s law.- This is important to see how light moves from one medium to another different medium and allows you to predict the bending that occurs in Snell”s law.
– Because the dispersive qualities of light.- The last color should be reddish due to the dispersive qualities of light. The particles in Earth”s atmosphere most effectively scatter shorter wavelengths of light, such as blue. Around the time of sunset, the sunlight travels a farther distance through the sky before it reaches our eyes. By the time sunlight reaches our eyes at sunset, the atmosphere has scattered most of the shorter wavelengths of light. Thus, we observe longer wavelengths of light, such as red and orange, during sunset.
Explain why the Moon appears to change colors during a total lunar eclipse (when Earth”s shadow completely blocks the light coming from the Sun).
If the Earth had no atmosphere, the Earth would completely block all sunlight from reaching the Moon during a lunar eclipse, and the Moon would be invisible. However, because of Earth”s atmosphere, light is scattered into the shadow cast on the Moon by Earth. Short wavelengths of light are more effectively scattered away by the atmosphere, but longer wavelengths, such as red and orange, will not be scattered as much and will reach the Moon”s surface. Thus, the Moon will appear red during a lunar eclipse.
Does the depth of a pool determine the critical angle that a light ray will have as it travels from the bottom of the pool and heads toward the air above the water? Explain your answer.
No, the critical angle only depends on the index of refraction of the material that it enters and that it reflects off.
The swimming pool seems shallower. If you follow a light ray that bounces off the bottom of the swimming pool and ends up entering your eyes, the light exits the water at an angle from the normal larger than the angle at which it arrived at the water-air boundary. This is because the index of refraction of water is greater than that of air. Your brain assumes that light travels in a straight line, so you interpret the origin of the ray on the floor of the swimming pool to be along the line of the light ray as it enters your eyes. The distance you measure to the origin of the light ray is fixed by your stereo vision, so the swimming pool appears to be shallower than it really is.
Fiber optics used for communication and laparoscopic surgery are two common uses of total internal reflection.
Recently, researchers have created materials with a negative index of refraction. Explain what happens to the angle of refraction if light enters such a material from air.
– The light would refract on the same side of the normal as the incident light beam. – When light enters a material with a negative index of refraction, the light refracts “back” away from the normal to the surface as seen in the picture below.
Describe how polarized sunglasses work. Why do such sunglasses have vertically polarized lenses (as opposed to horizontally polarized lenses)?
Polarized sunglasses use polarizing filters to absorb light that harms your eyes. Sunglasses have vertically polarized lenses because they block out the light that is horizontally polarized.
Soap bubbles reflecting different colors, thin-film coatings on photographic lenses (“nonreflective coatings”), and oil floating in a puddle of water are all examples of thin film interference.
A thin layer of gasoline floating on water appears brightly colored in sunlight. From where do the colors come?
These colors come from thin film interference. Part of each light wave striking the gasoline film reflects from the top surface, and part reflects from the bottom surface. These two reflected waves interfere with one another in a wavelength-dependent manner and make the layer appear brightly colored.
Does the phenomenon of diffraction apply to wave sources other than light? Give an example if it does.
Yes, diffraction occurs for all wavelike phenomena. Sound waves are diffracted through an open window and water waves are diffracted around an obstacle in the water, for example.
(Because scientists did not have the right equipment to make openings closer to the size of the wavelength of light that they were using.) Since the laboratory demonstration of diffraction involved passing light through a rather small slit (on the order of the wavelength of the light itself), it took scientists a while to perfect techniques that allowed them to make such small openings. For example, when Newton performed the single slit experiment, he observed no interference effects because the opening was so much larger than the wavelength of the light that he was using. About 100 years later, Thomas Young was able to use slits that were much narrower (closer to the size of the wavelength of light that he was using) and the diffraction effects were much more easily observed.
Sunlight striking a diamond throws rainbows of color in every direction. From where do the colors come?
(Sunlight includes all of the colors of the rainbow, and the diamond separates them.)-Sunlight includes all of the colors of the rainbow, and one of the delightful aspects of a diamond is its strong dispersion. Each color of visible light, corresponding to a different range of wavelengths, will bend at different angles through a diamond so that sunlight is separated into its different colors as it passes through the diamond”s surface.
Linearly polarized light is incident at Brewster”s angle on the surface of an optical medium. What can be said about the refracted and reflected beams if the incident beam is polarized in relation to the plane of the surface?(a) parallel (b) perpendicular
(a) Some of the incident light is reflected and some is refracted. Both the reflected and the refracted beams of light will be polarized in the direction parallel to the surface of the boundary. (b) At Brewster”s angle, the perpendicular component is completely refracted. Therefore, no light is reflected in this case.
Which kind of wave can refract when crossing from one medium to another with the wave having a different speed in the two media?
(electromagnetic, sound, and water waves) Refraction and interference are general phenomena for all types of waves.
When light enters a piece of glass from air with an angle of (theta) with respect to the normal to the boundary surface, which of the following will occur?
(It bends with an angle smaller than θ with respect to the normal to the boundary surface.) Glass has a higher index of refraction than air, so the refracted ray will bend towards the normal in the glass.
Which phenomenon would cause monochromatic light to enter the prism and follow along the path as shown in the figure below?(into triangle, through and out)
(refraction) Refraction refers to the bending of a light ray when it enters a medium with a different index of refraction.
(red) The index of refraction for red light in crown glass is smaller than the index of refraction for blue light, which means the speed of red light is larger than the speed of blue light in crown glass.
Two linear polarizing filters are placed one behind the other, so that their transmission directions are parallel to one another. A beam of unpolarized light of intensity I0 is directed at the two filters. What fraction of the light will pass through both filters?
(1/2 I) The intensity of unpolarized light drops by a factor of two when it passes through a linear polarizer. The second polarizer does not affect the intensity of the light because the two polarizers are aligned (i.e., θ = 0).
Two linear polarizing filters are placed one behind the other, so that their transmission directions form an angle of 45°. A beam of unpolarized light of intensity I0 is directed at the two filters. What fraction of the light will pass through both?
A monochromatic light passes through a narrow slit and forms a diffraction pattern on a screen behind the slit. As the wavelength of the light decreases, the diffraction pattern does which of the following?
(shrinks with all the fringes getting narrower) The fringe width is directly proportional to the wavelength of the light.
A monochromatic light passes through a narrow slit and forms a diffraction pattern on a screen behind the slit. As the slit width increases, the diffraction pattern does which of the following?
(shrinks with all the fringes getting narrower) The fringe width is inversely proportional to the slit width.
The figure below shows two single-slit diffraction patterns. The distance between the slit and the viewing screen is the same in both cases. Which of the following is true about the width of the slits, a and b?a) shorter and tighter b) larger and wider
Engineering Electromagnetics (Irwin Electronics & Computer Enginering)8th EditionJohn Buck, William Hayt