I observed an object in the low power field and when I switched to high-power it was no longer in my field of?

I observed an object in the low power field and when I switched to high-power it was no longer in my field of view. Why did this happen and how can I prevent it from happening?|||its because when you go to higher magnification, your field of view becomes smaller, lets say, if you can see 1 mm2 in 10X, when you change the magnification to 40X, you can see only 0.25 mm2 of you field, so to see the rest of the field, you should move your slide,





so to find your subject, you should search whole field to find it, and consider that when you change the magnification you should also adjust the focus again,





if you dont want to search for your subject, each time you change the magnification, try to put your subject in the center of your field of view, so when you change the magnification, that would be still in the center, if it is not, there is something wrong with your microscope ...