What is street light?
Street light refers to the luminaire that provides lighting function to the road, and refers to the luminaire within the road lighting range in traffic lighting. Street lights are widely used in all areas where lighting is required.
It is really unimaginable to have no street lights in urban lighting. There is no street light, and a black road on the road can easily cause traffic accidents.
Street lights involve lighting technology and are suitable for street lights. The purpose is to design a high-efficiency electronic energy-saving street lamp with long life, low power consumption, high power factor and small current harmonic content. The high-efficiency electronic energy-saving street lamp comprises sequentially connected grid high-voltage discharge branches R1, C1, rectifier bridges D1-D4, power factor correction branches C2, D5, D6, high-intermediate frequency glitch filter branches L1, L3, high-frequency oscillation circuit BG1-BG2, start branch L2, C7 and lamp tube T; can save 80% energy than previous street lamps; harmonic content THD <25%, extending lamp life by 3-4 times.
It increases the quality of life by artificially extending the hours of light so that man can carry on despite the dark. … And you have street lights throughout the night because it’s dark throughout the night. Street lighting is a boon to drivers, riders, and pedestrians.
Leaving street lights on all night is responsible for a lot of extra carbon emissions, but what’s the alternative – turning them off? You can’t do that since these lights deter crime and help prevent car accidents, right? Wrong, actually.
Published in the Journal of Epidemiology and Community Health, a new study finds that street lights have no significant impact on safety. Researchers at two different colleges in London examined over 60 areas over the span of 14 years to see what kind of difference having lights made. In the end, they found no evidence that having bright lights, dim lights or no lights made any difference in helping to reduce automobile accidents or crime.
Though the study confirms that car accidents do happen more frequently at night, the lighting in a particular area seems to have no real effect. A collision was just as likely to occur on a street with ample street lights as it was on a road without any. Drivers who use their high beams in unlit areas have comparable vision to that that street lights provide anyway.
For crime, researchers looked at data on crimes that occur more frequently after dark: robbery, burglary, sexual assault, etc. Streets without lampposts were no more likely to be victimized by crimes than brightly lit streets, indicating that criminals are not, in fact, deterred by street lights as conventional wisdom dictates.
Considering our current battle against climate change, this research makes it hard to justify installing or even turning on existing street lights. Using so much electricity to brighten sparsely trafficked roads only makes sense when you can readily identify the benefits. Add to that the fact that street lamp light pollution is harmful to insects, birds and plants, and, from an environmental perspective, it seems like they’re not worth the trouble.
Many communities have already turned off their street lights – not to save the environment, but to conserve money. These budget cuts may have been contested at the time, but hopefully research like this study will be used to educate communities. “With local government funding having seen substantial cuts, reducing or dimming streetlights can free up vital cash to protect under-pressure services such as child protection, adult social care, collecting bins and filling potholes,” said Peter Box, an environmental spokesperson for the Local Government Association in the UK.
Of course, regardless of whether it has an actual effect on crime, street lights are like a placebo of sorts and other research demonstrates that people think they’re safer with them even if they’re not. If communities insist on lighting their neighborhoods at night for a sense of security, they ought to make a switch to LED street lights that collect sunlight during the day and use the energy to power the lights at night.
If a small amount of current flows from emitter to base, then a large amount of current can flow from emitter to collector. In other words, if the base is grounded, it turns the “switch” (the path from emitter to collector) on in this diagram. So when light shines on the photocell, it turns the transistor on, which energizes the relay’s electromagnet, which turns the light off. When it is dark, the photocell has high resistance, so no current flows through the base and the relay is not activated — the light is on.
In a real street light the circuit might be a bit more advanced, but not a lot. It has the CdS cell, the transistor and the relay, but might need more than one transistor depending on the size of the relay. It really is a very simple circuit!