Lights Definition and 172 Threads

I read in a science question/answer book that it is takes as much energy to turn on a fluorescent light as it doesn to run it for 1 hour. So if this is true, it would mean that if you plan on using the light again within an hour, it is more efficient to leave it on, rather than turning it off...

Circuit Help! Help! I am trying to design thsi circuit for some friends, however, having the 2 light bulbs in the circuit seem to "eat" all of the power, cuasing the laser to be VERY dim. Isn't there an electronic component taht i can jump across the light bulbs that will allow them to stay...

I need some help with a formula, I am constructing some aids for a class room demonstration on basic electricity. I am using lights to demonstrate series and parallel cicuits, also trying to explain some of the basic laws. My question, If I hook three 25 watt bulbs in series with a supply...

I was wondering how flourescant lights work, and how they eventually wear out. I'm not sure, but it seems that you just have halogen gas inside the glass tube, you pump some electricity into the gas, it excites the atoms and they give off light as their electrons go from higher energy levels...

1. In older houses, when a refrigerator starts up, the lights may dim briefly. When an electric heater is turned on, the lights may stay dimmed as long as it is on. Explain the difference. 2. Explain what is meant by the statement "a motor acts as a motor and generator at the same time." Can...

Hello, I'm having some difficulty in a physics question. The question is: To save fuel, some truck drivers try to maintain a constant speed when possible. A truck traveling at 81.0 km/h approaches a car stopped at the red light. When the truck is 94.6 meters from the car the light turns...

Why the stop lights at the back of cars are red ? Some say because red light is visible from far distances. If that's true, is any relation between this property of red light and its wave length ?

Hi, i have this question wrong in my intro statistics class and I'm wonder if someone could help me understand why. Thanks in advance. Heres the question: "A string of christmas lights contains 4 bulbs. The lights are wired in a series, so that if one fails, the whole sting would go dark...

http://www.kpho.com/Global/story.asp?s=1958424 The video linked [website] may be unavailable until the activity calms down a bit.

http://www.abc.net.au/science/news/stories/s818193.htm

hi all, In our school there is a geography fair and i was just wondering weather it is possible to create aurura lights model. i feel using a hologram a fairly good model can be made. But i want something more better. I hope some one can help me. :confused:

From: http://www.redcolony.com/articles/030115.html "Photon Reaction: Until recently, scientists believed that photons (light) had no mass, but recently, it was discovered that they did have mass. Light has mass. Light is reflected by reflective surfaces. For every action, there is an equal...

If two 55 watts light is connected to a car's 12v battery, what amp rating relay should I get? 55/12 = 4.5 * 2 = 9amps? right?

What happens? Now I was just thinking about this before I went to bed the other night... I was thinking of different variables and whatnot, but the main question, what happens to the light that is "projected" by the luminous bodies that are the headlights? Now of course, we are in a...

Please see the thread: https://www.physicsforums.com/showthread.php?s=&threadid=7946

If a person passes through 6 sets of independent traffic lights that have a probability of 0.7 to stop the person at any particular set. Then how would you figure out the probability of that person stopping on the 2nd and 6th sets only?

I am posting here since no specific claims are made. This seems to be a good example of... http://www.news24houston.com/content/headlines/?ArID=16799&SecID=2

[SOLVED] Lights interaction with matter When light (photons/waves/whatever) comes into contact with matter, what are all the possible outcomes? Anyone mind listing them out with an explanation for each?

"Then a shadow crosses the massive, polished Dome of the Rock.. And another shadow. Suddenly the air is swarming with mud-coloured jets and helicopters that have crossed the Mediterranean Sea. Tanks, like a colony of ants, charge across the desert. Bombs explode. Buildings tumble. The sky goes...

"Mysterious lights were videotaped emerging from the thirty-seven circles discovered in young wheat below the Ridgeway at Ogbourne St. George, Wiltshire, England, on Sunday, June 15, in a pattern nearly 600 feet in diameter." http://www.earthfiles.com/news/news.cfm?ID=551&category=Environment

Hello, I am asking about "cool lights" for a project I have boiling over on the back burner.:smile: I have heard about "cool lights" in the film industry. They are supposedly very cool... not hot. Even 50K lights used at night, to make it look like daylight, can be cool lights. The...

I have heard tales of the Marfa Lights and seen them on TV but never experienced them in person. Has anyone here had the experience? In case no one has even heard of them, the Marfa Lights are a phenomenon outside of Marfa, Texas where shortly after dusk bright lights appear at ground level...