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The speed of light like any other speed is measured in relation to the distance and time (Speed= Distance/Time. Example: 50miles/hour). Say one individual with watches set exactly at the same time stand from one another within a mile of distance, one turns on a flashlight at a specific moment in time. Then the other person indicates the exact moment when he saw the flashlight on. Apply the formula and that is how the speed of light can be determined. Galileo tried this exact experiment (with a lantern of course!), but failed to be conclusive. However, it was clear that speed of light was not infinite as though before. Only in 1676 that experiments based on the solar system made by Ole Chistensen Romer where closer from the speed known today as the speed of light(299 7924 458 Meter/Seconds).
One method that was one of the first to measure the speed of light was to shine a light through pinhole on a spinning disk. The light was then reflected off a mirror that was some distance away.
Since light travels so fast, it would normally be reflected back through the pinhole (provided everything was lined up properly). By adjusting the speed of the spinning disk and/or the distance, the pinhole could be made to move enough that the light would not pass through it. Then, by calculating the size of the pinhole, the speed of the disk, and the distance to the mirror, the speed of light could be calculated.This is the pinhole method.
Another method to measure the speed of red light is to use equipment that includes a LED (light-emitting diode) that emits a regular series of pulses of red light that are only 20 nanoseconds in duration.
(A nanosecond is 10-9 second)
That means the pulse of light blinks on for 20 billionths of a second or 20/1,000,000,000 second and blinks 40,000 times per second. Having such a short pulse allows the scientist to measure the difference in time it takes to travel two different paths. If the duration was longer, the distance traveled would have to be longer.
By splitting the light beam with a half-silvered mirror, one beam travels to a mirror 10 meters away and then back to a photo diode detector. The other beam is reflected off a mirror only a few centimeters away. The time difference for the two beams is about 67 nanoseconds, which can be displayed on a regular dual beam oscilloscope.
The total distance the light travels is 20 meters, which equals 0.02 kilometer (20/1000).
The speed of light is then:
c = 0.02 kilometers/67 x 10-9 seconds = 298,500 kilometers per second.This is how the speed of light measured.
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ViviI assume you mean the amount of light, not its color or frequency. The SI unit of luminous intensity is the Candela, and this emits light measured in Lumens, which is the quantity you will find quoted for light bulbs, as well as wattage. If the light source of 1 Candela emits light in all directions, it emits 4 x Pi lumens, so the number of lumens is related to the solid angle over which the light is emitted. There is also the Lux which is the number of lumens per square meter. This obviously falls off the further away you are from the source.
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What is the unit for measurement of light?
You cannot 'measure' light. However, there is the light-year, a measurement of the distance light can travel in one year. there are many. Lumens, cadlepower, foot candles and candelas. There are probably a few more.
What is the unit of measurement to measure the thickness of a DVD?
The unit of measurement to measure the thickness of a DVD is typically expressed in millimeters.
When converting from a larger unit of measurement to a smaller unit of measure you should?
Divide by the conversion factor to get the equivalent value in the smaller unit.
What is the smaller unit of measure used the more precise the measurement what does this mean?
The smaller unit of measure used is called a precision unit. Using a smaller unit allows for more detailed measurements, leading to greater accuracy in the final measurement. Essentially, the more precise the measurement, the smaller the unit used to measure it.
What unit of measurement do you use to measure mass on a triple beam balance?
We use grams (g) as the unit of measurement to measure mass on a triple beam balance.
