What is the least distance of distinct vision for a normal adult with normal vision?

Which scientist first explained the dispersion of light?

What is meant by the near point of the eye?

$A$ prism $ABC,$ with base $BC,$ is placed in four different orientations as shown. $A$ narrow beam of white light is incident on the prism as shown. In which of the following cases,after dispersion,the third colour from the top corresponds to the colour of the sky?

How can you identify the type of vision defect a person is suffering from by physically touching their spectacles?

Where is the image formed in an eye suffering from near-sightedness?