Is there any material which acts like a mirror to reflect sunlight as well as allows light to pass through?
Yes. Most transparent materials can be coated with thin film stacks that can tailor the reflectance to almost any desired value. Film stacks can be design to suppress reflectance almost entirely, at least at certain angles. The anti reflective coatings on glasses are of this type. They can also be tuned to allow certain wavelengths to reflect and others to transmit. And, by choosing materials carefully, the coatings can be either absorptive or non-absorptive. Metallic coatings for example work quite well as partial reflector/partial transmitters, but they also absorb quite a lot of the light that is not reflected. Glass is commonly used as the substrate for these devices when dealing with sunlight’s visible and near-infrared wavelengths.
Do mirrors reflect ultraviolet light?
First, what reflects the light, whether it is UV, visible or IR wavelength, is the metal coating on the mirror.The reflectivity of various metals is indicated here:Page on www.layertec.de Aluminum is a good reflector of UV, visible and IR light.However, if the aluminum is on the Back Side of a piece of glass, the glass will absorb most of the UV light and therefore, No, a back-face mirror will not reflect much of the UV light. Unless the glass is special glass that has a a high transmissivity for UV.If the mirror is front-face coated (merely polished aluminum), then yes, it should do a good job in reflecting the UV light.
If we put a giant mirror at 10 lightyears' distance from the Earth, would we be able to see 20 years back by looking into that mirror from Earth?
That’s correct in terms of distance, once the mirror was in place for 10 years you could see light that was 20 years old. However, there are some other serious problems.Light intensity. From a distance of 20 light years (there and back) the earth would be invisible even with a perfect mirror. Exoplanets like Gliese 581 c have been discovered at this distance but they can’t be seen, they are detected via tiny wobbles in their star.Size. To see the whole earth, and therefore to return the maximum light, a planar mirror would have to be the half the size of the earth. Creating such a mirror might be impossible even with unlimited resources.Alignment. The mirror - half the size of the earth - would need to be aligned to an accuracy of less than a centimeter for any returning light to hit the earth. For the bounce light to hit a particular telescope you would need to align it to molecular accuracy. Tiny effects like radiation pressure would constantly be pushing it out of alignment.Surface shape. The surface would need to be shaped to molecular accuracy. From that distance getting a reflection of anything sightly imperfect would be like trying to get a decent reflection off crumpled tinfoil. Again forces like radiation pressure, gravity, differential heating would be constantly warping the mirror. Even the tiniest bend would make the mirror fail.It would be possible to use other shapes, for example, a very, very slightly parabolic mirror would improve the returned light enormously, and allow a smaller mirror but make the alignment problem worse.Even with unlimited resources and very advanced technology I doubt this is possible but feel free to give it a try.
What are some good text message size jokes?
i dont wanna type this thing all day what are some goofy, dumb, hell even retardid jokes that i can text message to some friends. ex....how do you make holy water? (first text) the suspince builds up until they ask "how?" then i text.... boil the hell out of it =p
Do satellites have lights on them?
Almost certainly a satellite. The ISS is the one you see the most often, but the Iridium satellites are the brightest -- but they're only super bright when they're turned just the right way, working like a mirror to reflect light on you, so it only lasts a few seconds. Which is why they call them Iridium flares.) When you see two satellites taking the same path at nearly the same time, it's a good time to check to see if something is going to or coming back from the ISS, like a shuttle -- as that's the most common cause of that. In order to dock with the ISS, you need to enter almost exactly the same orbit (but not exactly the same orbit, or you'd never reach it.) Similarly, when leaving it, you start out in the same orbit and then slowly change it. As for the ISS being visible at a different time than when you looked, it's very easy to get confused about time zones (though 6am certainly sounds right -- it's always around dusk or dawn) with the Heavens Above site, or perhaps you got your location wrong -- it's easy to do.
How is visible light used for communication?
Many techniques have been developed through the centuries to send messages using visible light. Below are just a few examples.Mirrors were used since the ancient times to send signals.The heliograph, a more modern device, uses a mirror, tilted with a telegraph key, to reflect sunlight to a distant observer. The receiver sees flashes of light conveying a message according to a prearranged signaling code.Naval ships often use signal lamps to transmit messages typically with Morse code.Lasers can emit very strong coherent light. Laser technology enables very high speed data transmission via fiber optics.Furthermore, lasers can be used for communication without any cables to communicate from huge distances, particularly in space.
What are the advantages of Morse Code?
The best advantage of Morse Code is that is is the only means of communication that can get through any form of interference, making it the most reliable form of communication ever devised…even beating out todays computer and cyber communications systems.It is the only form of communications that doesn’t rely strictly on electricity to operate or function. Any metal on metal, wood on wood, sound making device…car/boat horn…air type if electrical is knocked out by Electro-Magnetic Pulse (EMP)…and light source…flashlight, even a mirror and sunlight…can be used to send and receive Morse Code messages.It is one of, if not, the oldest means of sound/light communications and the most reliable ever devised. Although a bit hard to pick up when learning it; as with anything else, practice makes perfect and in the case of Morse Code, your send/receive speed can and will pick up the more you use it. The major problem with that is, if you can send/receive 20 coded 5-letter groups per minute and the pron receiveing can only do 8–10 such groups per minute, that’s all the faster you can send your message; otherwise that person will miss characters and have to ask you to repeat them so thy can piece your words (5-letter groups) together for thm to make any sense to the final recipient of your message. Make sense?? It’s like having the top of the line equipment on a home network but your router is the oldest and slowest piece of equipment in the system and is slowing everything down because it’s not fast enough or doesn’t understand the data from the newer equipment on the network…thus creating what is called a ‘bottleneck’. Same with Morse Code, if one operator is slower sending/receiving than the other(s) you have a bottleneck in the communications…but it’s still a reliable means of getting the message out to who you need them to get to.
How long would it take to reach the Andromeda using today's technology?
A Bugatti Veyron’s top speed is around 270mph. If you could somehow modify the Bugatti Veyron’s engine so it reached the speed of light instead of 270mph, it would take about 2.54 million years to get there.Andromeda is 2,538,000 light years away, and at the speed of light, at which none other than light can travel, it would take 2.54 million years to just get there.The average human lifespan is 71 years. Therefore, if NASA decided to send a probe to Andromeda in 2018 (HIGHLY impossible):35,774 generations of humans would have set foot on Earth before the probe even reached Andromeda, though due to time dilation it would be possible for a human to travel further than their 71 active years at a constant speed of c = 300,000 km/s.Likewise, is a NASA spacecraft travelling at 28,000 km/h was sent towards Andromeda, it would take about 844.7 trillion hours, or 7 x age of universe, or just about 94.5 billion Earth years.And here we are, complaining about the long hours of schools and offices.