Question

The capacity of a normal human eye to see the smallest objects is:
(A) 5000nm
(B) 10000nm
(C) 18000nm
(D) 25000nm

Answer 1

Hint: As we know that, the capacity of a normal human eye to see the smallest objects is $100\mu m$ (micrometers.) The image sent to the eye by way of the lens increases, we see an object more easily, even though its physical size has not changed. Under normal lighting conditions (light source $$\approx 1000$$ lumens at height 600-700nm,viewing angle $\approx 35$ degrees) the angular size recognized by naked eye will be round 1 arc minute $={\displaystyle \frac{1}{60}}$ degrees=.0003 radians.

Complete step-by-step answer
According to the question, we know that the capacity of a normal human eye to see the smallest objects is $100\mu m$. Then we will convert the value of maximum capacity of a normal eye from micrometers to nanometers as follows:
 $100\times {10}^{-6}m=10000nm$
Therefore, the capacity of a normal human eye to see the smallest objects is 10,000 nm that is option B.

Hence the correct solution is option B

Additional information:
A human can see a smallest object with naked eye close up is one-tenth of a millimeter diameter 0.1mm. This is the ability of being able to see what color it is, whether it is dust, sand, or a tiny full stop. The eye includes a lens similar to lenses found in optical instruments such as cameras and the same physics can be applied.

Note:
Although the capacity of a normal human eye to see the smallest objects is a hundred micrometers, there is a minimum distance for comfortable viewing which is roughly at 25 cm.