why must a viewed specimen be centered in the field of view on low power before going to high power?

Answer 1

The higher the power, the smaller the area of the actual surface that is being magnified. So if the viewed speciman is off-center on low power, it may well be outside the view area at high power.

Answer 2

I hope you are talking about viewing specimens under a
microscope. If so, it is because the field of view is smaller
for the high power, and if you have the specimen centered
in the low power field, it's all the more likely to be in view
when you switch to high power.
What has this question to do with physics? I thought you
used a microscope for biology!

Answer 3

The low power objective gives you a much wider field of view so you can find what you're looking for more easily. When you switch to a higher power objective, whatever was in the center of your low power field of view will be magnified enormously. Anything off to one side won't appear in the high power field of view.

Answer 4

the better the magnification the smaller the sector of view. in case you have the objective on the sting of the sector at low potential and then change lenses to a extra robust potential the outer edges are not any further interior the sector. despite if it quite relies properly it is going to likely be interior the sector of view at a extra robust potential, you will no longer ought to circulate the slide around attempting to discover it.