Final answer:
The total magnification of a microscope is calculated by multiplying the magnification of the objective lens by the ocular lens. A magnification of 250,000 is not viable for a standard light microscope, with maximum magnifications typically around 2000x.
Step-by-step explanation:
To calculate the total magnification of a microscope, you need to multiply the magnification of the objective lens by the magnification of the ocular or eyepiece lens. When friends show you an image through a microscope with the given values of objective and eyepiece focal lengths, the resulting overall magnification is mentioned as 250,000. However, this value is not viable for conventional light microscopes as the maximum theoretical magnification is around 2000x.
A common microscope has an ocular lens that typically magnifies 10 times (10x) and a range of objectives that magnify from 4x to 100x. Therefore, for an example with a 40x objective lens and a 10x ocular lens, the total magnification would be (40x) (10x) = 400x. The diameter of the field of view will not be specified by just the magnification and the focal lengths; it also depends on the characteristics of the specific lens and microscope being used. To find the overall magnification, using the thin lens equation is necessary.