When using a microscope with a 10X ocular and the 40X objective in place, what is the total magnification?

To determine the total magnification of a microscope, you multiply the magnification power of the ocular lens by that of the objective lens. In this case, the microscope has a 10X ocular lens, which means it magnifies the image ten times, and a 40X objective lens, which magnifies the image forty times.

Thus, the calculation is as follows:

Total magnification = Ocular magnification × Objective magnification

Total magnification = 10X × 40X = 400X

This calculation confirms that the total magnification is 400X, making it the correct choice. The values given in the other options either misrepresent the multiplication of the lens powers or suggest magnifications that are not achievable with the specified lenses.