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Physics Assignment Answer each question draw/copy diagrams when appropriate? 1. How does a day /night rear view mirror work?

A [|prismatic] rear-view mirror — sometimes called a "day/night mirror" — can be [|tilted] to reduce the brightness and [|glare] of lights, mostly for [|headlights] shining directly on the eye level at night. This type of mirror is made of a piece of glass that is wedge-shaped in cross section—its front and rear surfaces are not parallel. On manual tilt versions, a tab is used to adjust the mirror between "day" and "night" positions. In the day view position, the front surface is tilted and the reflective back side gives a strong reflection. When the mirror is moved to the night view position, its reflectorized rear surface is tilted out of line with the driver's view. This view is actually a reflection off the non-reflectorized front surface. Since the non-reflectorized front surface allows most of the light to go through, only a small amount of light is reflected into the driver's eyes.

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2. How is a secondary rainbow formed?

We have followed the path of a ray of sunlight as it enters and is reflected inside the raindrop. But not all of the energy of the ray escapes the raindrop after it is reflected once. A part of the ray is reflected again and travels along inside the drop to emerge from the drop. The rainbow we normally see is called the **primary** rainbow and is produced by one internal reflection; the **secondary** rainbow arises from two internal reflections and the rays exit the drop at an angle of 50 degrees° rather than the 42°degrees for the red primary bow

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3. Why is the human vision blurred under water?

The key here is the index of refraction. Index of refraction is a number which describes the speed of light through a transparent medium, and is defined as the ratio of the speed of light in a vacuum to the s.o.l. through the medium in question. For instance, light travels through water at about three quarters of its usual speed, so the index of refraction of water is about 1.33. By contrast, light hardly slows down at all going through air, so the index of refraction of air is just slightly more than 1. If light strikes the boundary of two materials (with different indices of refraction) at an angle, it'll pass into the other medium at a different angle. []

4. What are sundogs and how are they formed?

Sundogs are bright areas on either side of the sun usually superimposed onto an ice halo. Sundogs are also known as mock suns but they are more properly called parhelia. Sun dogs are formed when sunlight is refracted by 22 degrees through the flat plates of hexagonal ice crystals. The observer then sees two apparent images of the sun approximately 22 degrees on either side.

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5. What does it mean to have polarized light?

A light wave that is vibrating in more than one plane is referred to as unpolarized light.Polarized light waves are light waves in which the vibrations occur in a single plane. The process of transforming unpolarized light into polarized light is known as polarization.

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6. How has the speed of light been measured in the past by Galileo?

In the early 17th century, many scientists believed that there was no such thing as the "speed of light"; they thought light could travel any distance in no time at all. Galileo disagreed, and he came up with an experiment to measure light's velocity: he and his assistant each took a shuttered lantern, and they stood on hilltops one mile apart. Galileo flashed his lantern, and the assistant was supposed to open the shutter to his own lantern as soon as he saw Galileo's light. Galileo would then time how long it took before he saw the light from the other hilltop.

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7. According to the legend, the Roman Fleet at Syracuse was burned when Archimedes focused the sun’s rays using a large converging mirror. Was this practical?

Another story is that he focused the Sun's rays with mirrors on the ships to set them afire, but this is unlikely. Archimedes had investigated the parabola and therefore might have once demonstrated how to set fire to a nonmoving object from a distance with solar radiation focused by a parabolic mirror. But technology of that time -- or this, for that matter -- was not up to creating a mirror with the light-gathering power and focal length as any use as a weapon of war.

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8. How is Blue Ray different from High Definition (HD) format?

While current optical disc technologies such as DVD, DVD±R, DVD±RW, and DVD-RAM rely on a red laser to read and write data, the new format uses a blue-violet laser instead, hence the name Blu-ray. Despite the different type of lasers used, Blu-ray products can easily be made backwards compatible with CDs and DVDs through the use of a BD/DVD/CD compatible optical pickup unit. The benefit of using a blue-violet laser (405nm) is that it has a shorter wavelength than a red laser (650nm), which makes it possible to focus the laser spot with even greater precision. This allows data to be packed more tightly and stored in less space, so it's possible to fit more data on the disc

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9. What is dual layered DVD and how is it different then a regular DVD?

10. What is a Fresnel lens how is it different then a regular lens?

It is flat on one side and ridged on the other. Fresnel lenses we first used in the 1800s as the lens that focuses the beam in lighthouse lamps. Plastic Fresnel lenses are used as magnifiers when a thin, light lens is needed. The quality of the image is not nearly as good as that from a continuous glass lens, but in lots of applications (like your RV), perfect image quality is not necessary.The basic idea behind a Fresnel lens is simple. Imagine taking a plastic magnifying glass lens and slicing it into a hundred **concentric rings** (like the rings of a tree). Each ring is slightly thinner than the next and focuses the light toward the center. Now take each ring, modify it so that it's flat on one side, and make it the same thickness as the others. To retain the rings' ability to focus the light toward the center, the **angle** of each ring's angled face will be different. Now if you stack all the rings back together, you have a Fresnel lens. You can make the lens extremely large if you like. Large Fresnel lenses are often used as ­solar concentrators.