Calculation of Magnification

1. Each lens in a microscope produces an image with a certain magnification.

2. Lenses in the microscope are found in the objectives and eyepiece of the microscope.

3. The eyepiece lens has a magnification of 10X. This means it will make the specimen appear ten times larger than it really is.

4. Each objective has a different power of magnification. The power of the magnification is written on the objective.

a. In a microscope with three objectives the lowest power objective is usually 4X, the medium power objective is usually 10X and the highest power objective is 40X.

b. Sometimes a microscope has a fourth objective called the oil immersion objective. Its power of magnification is 100X.

5. When a specimen is observed, the total magnification seen includes that produced by the objective used to view it and the eyepiece. To calculate the total magnification you see use the following formula:

Total magnification = objective magnification X eyepiece magnification

6. If necessary, review the example below to help you in your calculations.

A specimen is viewed with the 4X objective.

Objective magnification = 4X

Eyepiece magnification = 10X

Total magnification = 4 X 10

Total magnification = 40X

This means that when viewed with the 4X objective, the specimen appears 40

times larger than it is.