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In some cases, it is possible to see flicker at rates beyond 2000 Hz (2 kHz) in the case of high-speed eye movements or object motion, via the "phantom array" effect. [ 16 ] [ 17 ] Fast-moving flickering objects zooming across view (either by object motion, or by eye motion such as rolling eyes), can cause a dotted or multicolored blur instead ...
Frequency (symbol f), most often measured in hertz (symbol: Hz), is the number of occurrences of a repeating event per unit of time. [1] It is also occasionally referred to as temporal frequency for clarity and to distinguish it from spatial frequency.
The human eye is relatively insensitive to indigo's frequencies, and some people who have otherwise-good vision cannot distinguish indigo from blue and violet. For this reason, some later commentators, including Isaac Asimov, [13] have suggested that indigo should not be regarded as a color in its own right but merely as a shade of blue or ...
1 centihertz (cHz) ~16.667 mHz: One rpm: 10 −1: 1 decihertz (dHz) 189 mHz: Acoustic – frequency of G −7, the lowest note sung by the singer with the deepest voice in the world, Tim Storms. His vocal cords vibrate 1 time every 5.29 seconds. 10 0: 1 hertz (Hz) 1 to 1.66 Hz: Approximate frequency of an adult human's resting heart beat: 1 Hz
Each color on top has approximately the same luminance level and yet they do not appear equally bright or dark. The yellow (second from the left) appears to be much darker than the magenta (right-most). However, when the top image is converted to grayscale, we have the image on the bottom--a single shade of gray.
The rate of alternation required to eliminate noticeable flicker depends on image brightness and other factors, but is typically well over 30 image pair cycles per second, the maximum possible with a 60 Hz display. A 120 Hz display, allowing 60 images per second per eye, is widely accepted as flicker-free.
The total number of genes that contribute to eye color is unknown, but there are a few likely candidates. A study in Rotterdam (2009) found that it was possible to predict eye color with more than 90% accuracy for brown and blue using just six SNPs. [16] [17] In humans, eye color is a highly sexually dimorphic trait. [18]
The main point I was trying to make is that the coherent SI unit for frequency is one per second—not one "cycle" per second (or one "sample" per second)—sometimes written as 1/s or s –1 (the latter called a reciprocal second)—and, since frequency refers to periodic events, one per second is given the special name hertz and symbol Hz. A ...