microscope lens question

[jjunior]

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29. For a microscope, where should the object be placed?
A. Inside the focal length of the objective
B. Just outside the focal point of the objective
C. Far away from the focal point of the objective
D. As close to the objective as possible

the answer is B, just outside of the focal point.
im wondering if one of the choice is just inside of the focal point, would it work as well? despite that it forms a virtual upright image instead of a real inverted one?
Thank you~😍

 

[frochocinco]

You sort of answered your own question. Placing the object inside the focal length would likely be the worst option...if you think back to your physics class or whichever review book you are using, you will remember that the lens of our eye is a convex lens, therefore, forming a real, inverted image on your retina at the focal point at the other side of the lens (convex lens have two focal points).

choosing to place the object inside the focal length, as you said, will form a virtual upright image, something that your retina will not be able to properly convert to a "comprehendable image" in your brain...lastly, the reason why it is just outside the focal length and not far from it (choice C), is because drawing ray diagrams will indicate to you that the closer the object is to the focal length, the larger the image appears, and thus, as you are using a microscope to magnify an image that is "microscopic", you would want the image to be as big as possible.