What part of the microscope is directly affected when using immerse oil?

When using immersion oil, the part of the microscope that is directly affected is the objective lens. Immersion oil is used to increase the resolving power of a microscope when observing specimens at high magnification. The oil has a refractive index that is similar to that of glass, which helps to reduce the loss of light due to refraction as it passes from the oil into the lens and then into the glass slide. This improves image clarity and resolution.

Using immersion oil requires that the lens is designed for it, typically the higher magnification objective lenses. The oil creates a continuous optical path between the specimen and the lens, which minimizes light scattering and enhances the details seen in the specimen. Without the appropriate objective lens designed for immersion oil, the benefits of using the oil would not be realized, potentially leading to poor imaging or possible contamination of the objective.