Sort Order: Closest first Highest first Lowest first. It's about 10,, times as long as The First airplane flight Wright Flyer, In other words, 35, hours is 11,, times the length of The First airplane flight Wright Flyer, , and the length of The First airplane flight Wright Flyer, is 0.
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Why is there so much bad information out there? Are manufacturers just fudging their claims, or are there other pieces to the puzzle? Well, though we frequently stress the importance of vetting manufacturers, and manufacturer reps, a lot of this bad information just comes down to the industry adjusting to a new, still emerging and evolving lighting technology. That said, we're not here to make excuses for misleading or inaccurate lifetime claims. We're here to make the technicalities behind these inaccuracies understandable, so that you can effectively avoid the risk of getting left high-and-dry with early failures or poor light quality from LEDs.
LED life ratings have to be measured differently than legacy lighting sources, because the technology is just so much different than anything we've ever seen. We're here to make lighting easier , as we like to say. Not to beat you over the head with lighting terminology. But these distinctions are important, so let's take a second to define what, exactly, all of this means.
As defined in our downloadable lighting glossary , average rated life is:. Manufacturers use three hours per start for fluorescent lamps and 10 hours per start for HID lamps when performing lamp life testing procedures.
Every lamp type has a unique mortality curve that depicts its average rated life. This is the de facto metric for measuring the life expectancy of traditional light sources. LEDs, however, follow a different method for measuring life expectancy called lumen maintenance.
Lumen maintenance is an approach of measuring the light output lumens of a brand new light source and comparing that with its light output after a certain period of time. L70 and L50 are examples of lumen maintenance — benchmarks for when 70 or 50 percent of a lamp or fixture's total light output remains. In it, they explain:. We've written about a lot of this stuff before, specifically in this article about LED warranties. What makes the recent DOE report interesting, and worth writing about and re-hashing some of this, is the pointedness of its determination that the way we think about LED lifespan ought to be totally different than the way we've traditionally thought about the lifespans read: life ratings of conventional lighting products.
For decades, we've been replacing light bulbs after they burn out. One day, we walk in a room and flick a switch, and there's either a flash, or the light simply won't turn on. But LEDs can exist on a kind of life support for quite some time after their point of optimal usefulness, so we have to look for a different sign to know when to replace them.
It's impractical to take these fluctuations into account. They sometimes cancel out, but more often they don't. Because they affect the elapsed time and your average speed, they may lead to an inaccurate relationship between the distance traveled and the time taken to travel it.
On some paper maps, you'll find charts listing the distances between major cities and the time it takes to travel between them. You can use them to convert between miles and hours, but there's a better way. Smartphone map apps are more accurate because they monitor traffic, which can sometimes make the difference between a 2-hour trip and a 6-hour one.
Traffic conditions are constantly changing, and driving time estimates on smartphone maps change with them. Some apps even suggest alternate routes to your destination that, due to current traffic conditions, will get you to your destination faster than the main route.
If it's important for you to know how many hours it takes to drive a certain number of miles, your best bet is to download a live map app and use it. Just be sure to pull off the road before you check it. Chris Deziel holds a Bachelor's degree in physics and a Master's degree in Humanities, He has taught science, math and English at the university level, both in his native Canada and in Japan. He began writing online in , offering information in scientific, cultural and practical topics.
His writing covers science, math and home improvement and design, as well as religion and the oriental healing arts. Related Articles What is Speed?
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