Oil immersion objectives are preferred in a microscope because they provide higher magnification and resolution. The use of immersion oil helps to increase the numerical aperture of the objective lens, allowing more light to be collected and resulting in a clearer image. The oil also reduces the amount of light that is lost due to refraction and scattering, which can occur when light passes through different mediums of varying refractive indexes. This allows for a more detailed and sharp image to be observed. Oil immersion objectives are commonly used in applications that require high magnification and resolution, such as in microbiology and histology.
