Lights Definition and 173 Threads

Homework Statement A truck is stopped at a traffic light. The moment the light turns green, it begins to accelerate constantly at 3.1m/s^2. A cyclist approaching the truck from behind with a constant velocity of 10m/s was 7.5m behind the truck when the lights turned green. 1)How much time...

How do these LEDs conduct ? With this board: the associated schematic is: P1 (with pins 1 and 2) represents a motor. OUT1 and OUT2 are the conduction paths. LEDs L2 and L1 will illuminate depending on which way the H-Bridge is conducting. My question is how are is that the...

There will be some heavy sunspot activity when the solar poles flip... should be some good aurora's...but how far south will they be viewable? Regards, Jack Martinelli

Homework Statement A police officer pulls you over for running a red light. You tell the officer, “But the light looked green to me!” How fast would you have to be traveling for this statement to be true? Homework Equations ? The Attempt at a Solution Can anyone point me in the...

Hello this is Julia. I wanted to build a model with a probability problem with the following. Consider the intersection of two roads controlled by a traffic light. The model should consider probabilistic the arrival of automobiles in each direction. Then evaluate how you would set the timing...

Hello, I was just looking up some pictures when I saw a picture of the northern lights. I was told that it was something to do with electricity? What actually happens up there? Thanks

I am considering purchasing an in-car camera such as this: http://www.ebay.com/itm/Vehicle-Car-DVR-Recorder-Camera-Road-Safety-Guard-6-LED-270-2-5-TFT-LCD-Screen-/281082214101?pt=US_Surveillance_Digital_Video_Recorders_Cards&hash=item4171ce36d5 The device has six infrared lamps to...

I always wanted to know how this worked? I know AMPs is how many Electrons move past one point in a SEC. I know that Voltage is the Force that drives the AMPs. I know that a House Outlet will supply 120 Volts at 15 Amps. Now take Christmass Tree Lights and to keep this easy let's...

Hey, I want to make a get better poster with led light sticking out of the poster. I found the following LEDs: http://www.play-zone.ch/de/bauteile/led/led-sortiment-mit-180-leds-oem.html . I have very little experience with wiring circuits (did AP physics a while back) and I'm not sure if this...

I have studied,as one of the uses of polaroids is, that it can be fitted in the head lights of cars and other vehicles to eliminate the glare. This will certainly act as a boon to the motorists and result in considerable reduction of road accidents during the night time. I have also learned...

I have Led lights in the house ceiling fixtures running on household AC when the are switched off they still give a small amount of light am I paying for this current or is this current that would have been lost anyway? John

I have seen some questions and responses in this regards in this forum. I am not very convinced, so I shoot the question again. Is it possible to feed PV cells with LED lighting? With LED's coloured lighting is easier, and getting a frequency in the range rated for a panel is easier. But...

Hi all, Can anyone tell me if semen stains would definitely glow under a black light (UV light) ? I've been told that they would glow in greenish-yellow under the UV light. But later on someone said semen stains cannot glow without a substance called 'luminol'. Which one is true...

If any group of people can help me with this interesting one it's you folks. So I hope most of you have seen that wonderful video of the ISS flyover of the Earth. In case you haven't for reference... Other than being blown away like everyone else something particular caught my eye, and after...

Homework Statement 1. A soap bubble is colored because of: a. dispersion b. diffraction c. thin film interference d. all of the above Homework Equations The Attempt at a Solution I don't understand the concepts very well...at first I though the answer was dispersion...

Homework Statement A decorative light fixture in an elevator consists of a 2.0 kg light suspended by a cable from the ceiling of the elevator. From this light, a separate presses the emergency stop button. During the stop, the upper cable snaps. The elevator engineer says that the cable could...

An LED lights up when i touch it. One leg is attached to a piece of metal, other is the one i touch. Polarity does not matter. Amount of metal maters - table frame makes it full bright, half-meter steel ruler makes it dim, a piece of wire makes it just visible. Touching that piece of metal...

It might be Happy Hanukkah, Happy Chanukah, Chanukkah, or Chanuka...for all I know it could be Chappy Hanukkah. Whatever it's called, I hope all our Jewish PFers have a wonderful holiday!

What is the main frequency components of noise from AC line, florescent lights, appliances and other common household stuff? I know there are 60Hz and 120Hz from rectifying. Do I have to worry about 180, 240, 300, 360 ( 60X1, X2, X3, X4, X5...) etc.? Which one are the strong ones?

Homework Statement ceiling light are connected in a parallel circuit, if one of the light bulbs burns out, will the other two bulbs be brighter? pls help me >.< my science exam is tomorrow.:(

Hi, I do not know anything about relays. I been trying for days to hook up a relay to turn on a light using an Axis camera with an I/O switch. This is the relay http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=105585863&uq=634536768231996536&DPU=submit This is the manual...

Hello! I have waaaay to much time on my hands due to an illness and bought a bunch of items on ebay to play with and keep my time occupied. I bought a bunch of 12v smd led car bulbs and want to power them through my existing 110v wiring, I can handle fitting the bulbs into the existing...

If a car is traveling towards you and turns on the lights the speed of light would be c, but if the car was traveling away from you and turned the lights on would the speed of light be c or less than c? I've tried to search this question, but it's not easy to describe in a search engine!

Hi. I've searched this forum before for answers and it has never failed me before. I've seen threads on similar if not the same topic as this on here but they are either from years ago or the threads have been closed. So here's the story, so tonight my brother in-law is at work and during...

For my physics house project, it says i have to have 2 lights connected in parallel with one switch and unequal brightness, using a resistor. Is there anyway to do this?

How to design a ciruit that has 2 LED Lights ... I want to design a circuit for the sake of me seing if i can do it. I need the following things 2 LED Lights which are flashing on and off and make noise relative to when there on or off ( like a police siren ) and also i need to house all of...

I'm not sure if anyone knows, or if this really is a physics question, but I was wondering why bright lights always seem to have rays emanating from them. What I mean by this is that bright lights, such as the sun or a car's headlight, always seem to radiate light in visibly distinct bright...

I volunteered to help out with a research project, and we need a solution for a way to filter out light of the blue wavelength from a light source. THe blue wavelength is the only wavelength we want to remove. I was wondering if anyone here had any suggestions? Someone from the project suggested...

I am trying to take two lights and usign a 9v battery switch between the LED's. My thought was if i could get a square wave to go from positive to negative, since the LED's are polarity sensative I could just put them in parallel with the positive of one and the negative of the other being fed...

hi i have noticed a pair of zig zagging lights about 6 months ago when i was having a smoke break, i decided to take a closer look and for the last 6 months I've been watching them everyday...they are there every night, i have even shown friends and family and they saw the same thing...it really...

hey everyone, I don't really know about the electrical of a car system. but i intend to need some help an guidance from you all about installing some decoration lights for an automobile.All i know the car uses a 12V lead-acid battery and has an alternator which charges up the battery when the...

Hi ppl, I have a question to you. What happens if we approach two lasers with different wavelengths close together while they going in the same direction? ----------------> -.-.-.-.-.-.-.-.-.> did we get the interference between the different wave length of lasers result the different...

Dont ignore this as a hypothetical one, but really I have some doubt... suppose we made a very bright torch light and took it to Mars. Now assuming that the light is bright enough for me to observe it from Earth with the naked eye, would we see the light twinkling? Is the twinkling only...

Why can't our eyes focus on that one type of deep blue Christmas lights? It always appears fuzzy from a distance, even if another bulb right next to it appears in focus.

It will be obvious that I am not a certified Electrical Engineer. I am trying to create a small display and using LED lights to "accent" the display. I was wanting to use 6 to 9 LEDs in a circular fashion. What I am not certain of is: Can I run 6 - 9 LED's just by using a power cord and...

I am aware that the human body has electrical properties, But was baffled by what I witnessed Christmas Eve. I had a malfunctioning electric candle in the window. I picked it up to check the tightness of the bulb, and it immediately came on. I set it down and it went off. Three times this...

http://www.physorg.com/news/2010-12-ibm-breakthrough-chip-technology-path.html Can Microsoft or AMD use this Nanophotonics chip technology? Can they say goodbye to Moore's Law after this breakthrough?

Hi! I did a laboration on detecting different wavelenght from a UV-c light tube and the electrometer detected some activity from the Monochromator in the area of visible light (400nm-700nm). I would like to know if this has something to do with the quality of the light tube? Or does something...

Hi I am curious about a few things i have read about light and would appreciate some help. First of all to my knowledge the speed of light is 186,000 mps and of course its impossible to exceed or reach the barrier of light for any other object other than light. But I am curious as to why...

I'm a mechanical (mecha-nickel) engineer and not an electrical engineer, so please don't kill me for asking: In a fluorescent light the high voltage potential between each end of the light strips the electrons from the mercury gas which ultimamately generates UV light, etc., etc. My...

Hello... this is my first post and it involves a question that I have regarding Electromagnetic Fields and their relationship to the Human Body. The reason for this inquiry is due to a phenomenon I've experience since I was about 7 years old. However, I've not really given it much thought until...

What is in your opinion most promising technology -LED or induction light?

I'm sure this is a silly question. My understanding of waves would suggest that it should be possible to put two (small) light sources side by side in such a manner that no light energy reaches most observer positions, yet my understanding of electromagnetism is insufficient to confirm this...

What do inductive ballasts, like those used in fluorescent lights, do to power factor?

http://www.google.com/hostednews/ap/article/ALeqM5jTPC5ic6tJh9PiHscwgOANkJ17-wD9EN05NO0 I don't think a lot of energy will be saved, but perhaps the sky will be a bit darker, perhaps allowing us to see such things like the zodiacal light: http://en.wikipedia.org/wiki/Zodiacal_light

The Northern Lights - aurora borealis - may be visible tonight south of the 45 parallel. http://www.swpc.noaa.gov/pmap/gif/pmapN.gif http://www.swpc.noaa.gov/pmap/pmapN.html

have been told there is a way to make this mystery below work and can't figure it out. I know it wouldn't be up to code and i would never do it but if someone could hook me up with a wire diagram of how its done i really appreciate it. I am pretty sure switching the neutral is involved...

mobile "lights" I have seen some light making stickers sold that can be put on your mobile and they emit light when you talk. Am I right that they will lower my chances of getting connected when I am far from the antenna? I mean they must somehow make signal weaker, don;t they?

http://www.dailymail.co.uk/news/worldnews/article-1234430/Mystery-spiral-blue-light-display-hovers-Norway.html I don't for one second believe this was a failed rocket, and anyone who does surely is a gullible fellow. Firs the Russians denied it being a Rocket, and than two days later they...

First of all, I'll say that I do not have much experience in electronics, but I am relatively competent. So, to the point; have any of you seen those outdoor path lights that have a solar cell on the top of them? They charge during the day and light up with LEDs at night. Does anybody know...