Question

A student has the high-power lens in position and appears to be intently observing the specimen. The instructor, noting a working distance of about 1 cm, knows the student isn't actually seeing the specimen. How so?

Answer 1

Answer:

Explanation:

Based on this the student is out if the focus, and just viewing on  the dust.Basically, high -power lens is a non oil immersion lens, with a short working distance  of 1cm,which  will be about  a few millimeters.Hence the student will be out of focus, just carry out a fruitless effort  focusing on the dust, missing the focus on the specimen.