Big, Bigger, Biggest

Name Date Class

Light ■ Enrich

Big, Bigger, Biggest

The magnification, or power, of a lens or a microscope is how much larger than normal the instrument makes the viewed objects appear. The symbol used to indicate magnification is x. For example, a 100x microscope makes objects appear 100 times larger than normal.

The magnification of a microscope depends on the magnifications of its eyepiece and objective. Other characteristics of microscopes, such as field of view and brightness, also change as the magnification of the microscope changes.

The table below shows the magnification of a microscope with the various combinations of 12x and 15x eyepieces with 15x, 43x and 97x objectives. It also shows how field of view and brightness change. Field of view is how much you can see, top to bottom and side to side. In general, the wider the field of view, the better. You want brightness to be high so that details can be seen easily. The bottom two rows are left empty for you to use when answering Question 4.

Power
Eyepiece Lens / Objective Lens / Magnification / Field of View / Brightness
12x / 15x / 180x / wide / bright
12x / 43x / 516x / less wide / less bright
12x / 97x / 1,164x / least wide / least bright
15x / 15x / 225x / wide / bright
15x / 43x / 645x / less wide / less bright
15x / 97x / 1,455x / least wide / least bright

Answer the following questions on a separate sheet of paper.

1. How do you calculate the magnification of a microscope from the magnification of the eyepiece and objective?

2. How does field of view change as magnification changes?

3. How does brightness change as magnification changes?

4. Fill in the bottom two rows to compare the magnification, field of view, and brightness of a microscope that has a 12x eyepiece and a 50x objective with a microscope that has a 10x eyepiece and a 43x objective.