Final answer:
C) empty magnification
The term for when the magnification power of a microscope exceeds its resolving ability is 'empty magnification'. This results in images that are larger but blurrier, offering no additional detail.
Step-by-step explanation:
When magnification power of a microscope exceeds the scope's ability to resolve, the term used to describe this is empty magnification. This phenomenon occurs because, while the image gets larger, it does not become clearer, thus providing no additional detail.
An example of this would be trying to read fine print with a magnifying glass; as you increase magnification, the words become larger but also blurrier. This is because the resolving power of the lens is surpassed. Resolving power is determined by factors such as wavelength and numerical aperture (NA), which relate to a lens's ability to gather light and provide detailed imagery.
The practical limit of resolution for most light microscopes is about 0.2 µm, due to diffraction limitations of light waves. To improve visibility of specimens that lack contrast, staining with selective dyes can be helpful. Moreover, an oil immersion lens is commonly used to achieve high magnification while maintaining resolution.
Overall, without sufficient resolution, a clear and detailed observation is not possible even with higher magnification levels.