Passage IV

The total magnification provided by a compound light microscope is determined by multiplying the power (magnification) of the ocular lens (eyepiece) by the power of the objective lens. The area seen when looking through a microscope is called the field of view (FOV). The diameter of the FOV varies with total magnification. Table 1 gives the power of, and the FOV diameter associated with, 4 different objective lenses on a microscope (Microscope M) with an ocular lens power of 10x. Table 2 lists 4 types of microscopic organisms found in pond water and gives their size ranges and their distinguishing characteristics.

23. The figure below shows an organism viewed through Microscope M using 1 of the 4 objective lenses. The organism is the largest specimen of its type. Based on ables 1 and 2, which objective lens is being used to view it?

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

It can be seen from the figure that the creature is paramecia paramecia. According to table 2, its size range is 0.05-0.35, so an objective lens with FOV slightly larger than 0.35 should be used.

Corresponding to table 1, it can be seen that the FOV of Lens 3 is 0.4, and you can just see the paramecia with a size of 0.35