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Physics Assignment
1. How does a day /night rear view mirror work?

A day/night rearveiw mirror usually had a tab underneith the mirror to switch from day mirror to night mirror. When the mirror is at the day light settings the mirror is facing straight back through the rear window. When the mirror is at the night time setting the mirror ends up to be in a wedge type shape which the mirror side of the mirror shows you the dark roof of the car. There is a reflective coating on the other side of the mirror which reflects the road which will natually have more light from the car behind you. So both front and rear sides are actually reflecting the light to you.

[] 2. How is a secondary rainbow formed?

A rainbow is formed usually by suns rays reflecting in a spherical rainbow formed raindrop. A secondary rainbow is formed when there are more than two rays being reflected in the raindrops. Usually in the raindrop of a secondary rainbow there are many different ray paths. Compared to a Primary raindrop the rays are closer to the edge of the raindrop then the other. The inside rainbow is always more prominent because of the bendin of sun rays.

[] [] 3. Why is the human vision blurred under water?

The curvature of the eye ball (specifically the lens at the front) is what focuses the light on to the retina at the back. When water comes into contact with the lens it changes its optical parameters. Swimming goggles stop this happening by keeping the water away from the eyes and usually, to stop any optical distortion of objects viewed, have perfectly flat surfaces through which you look.

[] 4. What are sundogs and how are they formed?

Sundogs are also known as mock suns they are a pair of brightly coloured spots on the sid of the sun. Sundogs form as sunlight is refracted by hexagonal plate-like ice crystals with diameters larger than 30 micrometers and their flat faces horizontally oriented. Sundogs are visible when the sun is near the horizon and on the same horizontal plane as the observer and the ice crystals. As sunlight passes through the ice crystals, it is bent by 22 degrees before reaching our eyes, much like what happens with [|22 degree halos]. This bending of light results in the formation of a sundog.

[] 5. What does it mean to have polarized light?  Polarized light can be used for several purposes. It is easy to see by it, so it can be used to filter light for sunglasses and protect your eyes from harmful rays from the sun. It is also used in microscopes to make aspects of a variety of plants more visible and easier to study.  Once light has been polarized, it has only one form of wave in it instead of two. Polarized light is created using polarized lenses, which only allow one type of wave of light to pass through the lens. For example, most polarized sunglasses block the "horizontal" waves of light and allow the "vertical" ones to pass through. If you place two polarized lenses on top of each other and rotate them until the filters are perpendicular to each other, you will be able to block all light from passing through.

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

In 1667, Galileo Galilei is often credited with being the first scientist to try to determine the speed of light. His method was quite simple. He and an assistant each had lamps which could be covered and uncovered at will. Galileo would uncover his lamp, and as soon as his assistant saw the light he would uncover his. By measuring the elapsed time until Galileo saw his assistant's light and knowing how far apart the lamps were, Galileo reasoned he should be able to determine the speed of the light. His conclusion: "If not instantaneous, it is extraordinarily rapid". Most likely he used a water clock, where the amount of water that empties from a container represents the amount of time that has passed. Galileo just deduced that light travels at least ten times faster than sound.

[|http://www.speed-light.info/measure/speed_of_light_history.htm#speed_of_light_galileo] 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?

The following report by J. L. Hunt tells us that it is not unlikely even if it is not clear how the motion of ships is considered in the experiments by Buffon and others. This argument is incomplete since he said nothing about the nature of the object receiving the focused energy. The total heat delivered by the mirror is not the point. What is important is the size of the image produced by the mirror and the characteristics of the surface being heated, particularly as to how it absorbs and conducts heat. in the ideal case of a perfectly black surface which loses no heat, then the surface temperature will rise to the same temperature as that of the Sun. This is well above the flash-point of wood which as all readers of Science Fiction know is "Fahrenheit 451". All children know that they can set fire to a piece of wood with a magnifying glass. They can do this because the small image of the Sun, which focuses on the wood acquires a high temperature; that amount of heat delivered is of lesser consequence.

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

The format was developed to enable recording, rewriting and playback of high-definition video (HD), as well as storing large amounts of data. The format offers more than five times the storage capacity of traditional DVDs and can hold up to 25GB on a single-layer disc and 50GB on a dual-layer disc. This extra capacity combined with the use of advanced video and audio codecs will offer consumers an unprecedented HD experience.

[] 9. What is dual layered DVD and how is it different then a regular DVD? In dual layer DVD-9 discs, two layers of standard DVD-5 are joined together with a transparent spacer and a thin reflector between the two. The bottom layer is read and written to in exactly the same manner as DVD-5. Reading and writing to the second layer is achieved by the laser focusing a fraction of a millimeter beyond the first recording layer. Single Layer DVD Dual Layer DVD

[] 10. What is a fibre optics cable? How much data can be sent down one fibre strand?

An **optical fiber (or optical fibre)** is a flexible, transparent fiber made of a pure glass (silica) not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of optical fibers is known as **fiber optics**. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Fibers are also used for illumination, and are wrapped in bundles so they can be used to carry images, thus allowing viewing in tight spaces. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers.

[|http://en.wikipedia.org/wiki/Optical_fiber#Single-mode_fiber]