Objective lenses

Definition

Objective lenses are the primary optical lenses on a microscope that magnify the specimen. They are typically located closest to the specimen being observed.

5 Must Know Facts For Your Next Test

1. Objective lenses come in different magnifications, commonly ranging from 4x to 100x.
2. The total magnification of a microscope is calculated by multiplying the ocular lens magnification with the objective lens magnification.
3. High-power objective lenses, such as the 100x oil immersion lens, require a drop of immersion oil between the lens and the slide for clear viewing.
4. Objective lenses are usually mounted on a rotating nosepiece to allow easy switching between different magnifications.
5. The quality of objective lenses can greatly affect image resolution and clarity, making them critical components in microscopy.

Review Questions

• How do you calculate the total magnification of a microscope?
• Why is immersion oil used with some high-power objective lenses?
• What is the function of the rotating nosepiece on a microscope?

Related terms

Ocular Lens:

The eyepiece through which a person looks into a microscope, usually providing additional magnification.

Resolution:

The ability of a microscope to distinguish two close objects as separate entities.

Stage:

The platform on which slides holding specimens are placed for observation under a microscope.