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The human eye has an approximate angular...

The human eye has an approximate angular resolution of `phi = 5.8xx10^(-4)` rad and a typical photo printer prints a minimum of 300 dpi (dots per inch, `= 2.54 cm`). Aminimum distance 'z' should a printed page be held so that one doesnot see the indivdual dots is ______ .

Text Solution

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Given, angular resolution of human eye,
`phi = 5.8 xx 10^(-4) rad`
The linear distance between two successive dots is
`l = (2.54)/300 cm = 0.84 xx 10^(-2) cm`
At a distance of z cm, angle subtended is
`phi = l/z`
`implies z = l/(phi) = (0.84 xx 10^(-2))/(5.8 xx 10^(-4)) = 14.5 cm`
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