A website with a database of information on a variety of units of measure. Look for new perspectives on the magnitude of any physical quantity. Contribute your own unique "Perspective Block." Or do it the easy way -- ask the Units Guy how big or small. Explore & learn!
www.units-of-measure.com this month would like to recognize the the science curriculum of one extraordinary Middle School, Jr. High or High School:
W.H. Beasley Middle School
Please visit this months spot-light school's website and learn about how they achieve excellence in science education in their community.
...where middle school science flourishes in Casper, Wyoming.
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Ten nanoseconds is the demarcation time for the latent irradiance emitted from a material, which defines whether the emission is fluorescent or phosphorescent. For example phosphorescence is luminance or the emission of light from a source, which is delayed by more than ten nanoseconds following excitation. Glow in the dark items phosphoresce. Fluorescence is where the wavelength-shifted emission continues only as long as the stimulus producing it is maintained. Hence, the 10 nanosecond demarcation time. Many substances fluoresce in ultraviolet light (black light) including detergents and cat urine.
The Photonics Dictionary
Units Guy- Fort Collins, CO USA
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The read transition time for one user bit off of a ROM disk in the fastest CD drives on the market today is about 16 nanoseconds or 62.4 megabits/second. Typically, you will see CD speeds in groups of three numbers, for example: 2x1x8x. These speeds refer to the following functions of the CD drive: Writing to 'R' media x Writing to 'RW' media x Reading 'ROM' media (R = Recordable, RW = ReWritable, and ROM = Read Only Memory.) 1X CD transfer rate is defined as 150 kilobytes/second (KB/s). Today’s peak performance CD/CDRW drives are rated at 52x32x52x or 7.8 MB/s – 4.8 MB/s – 7.8 MB/s (megabytes/sec).
The promised minimum data transfer transition time for one user bit for Blu-ray drives is about 27.8 nanoseconds or a peak data rate of 36 megabits/second (Mb/s) or 4.5 megabytes/sec. (MB/s). As the format name directly indicates, a newly developed blue laser diode (405 nm) has been adopted as the optical stylus, providing a storage capacity of 25 GB on a single-layered disc or 50 GB on a dual-layered disc with a 12 cm diameter (same size as CD and DVD). The Blu-ray disc is held in a cartridge. The peak write transfer rate for presently (08/04) shipping Blu-ray drives from Sony Corp. is 24 Mb/s or 3 MB/s.
Blu-ray Technology Website
Units Guy- Fort Collins, CO USA
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The minimum data transfer transition time for one user bit for a removable hard disk (HD) is about 4.92 nanoseconds or a peak data rate of 24.5 megabytes/sec. (MB/s). The REV removable magnetic data storage drive from Iomega is presently the fastest performer in this data storage category. This drive uses 2 ½” diameter glass disks spun at 4200 RPM. This products maximum data transfer rate at the disk’s inner diameter (ID) is 12.7 MB/s while it’s maximum rate at the outer diameter (OD) is 25.4 MB/s. The rate difference is due to the difference in linear velocity of a disk at the OD versus the ID for a constant RPM.
The minimum data transfer transition time for one user bit for a shipping magnetic hard disk drive is about 1.45 nanoseconds or a peak data rate of 86 megabytes/sec. (MB/s). The Cheetah 15K.3 magnetic storage hard drive from Seagate is presently the fastest performer in this data storage category. This drive uses 3 ½” diameter disks spun at 15,000 RPM. This products maximum data transfer rate at the disk’s inner diameter (ID) is 52 MB/s while it’s maximum rate at the outer diameter (OD) is 86 MB/s. The rate difference is due to the difference in linear velocity of a disk at the OD versus the ID for a constant RPM.
