Final answer:
Resolving power is the ability of a lens to distinguish two closely spaced objects as separate, with a higher resolving power indicating a smaller minimum distance 'x' for resolution.
Step-by-step explanation:
The term resolving power refers to the ability of a lens, such as in a microscope or telescope, to produce sharp images of two closely spaced point objects. It is defined by the minimum distance at which two objects can be distinguished as separate. The smaller this distance, represented by 'x', the higher the resolving power of the lens. This concept is frequently discussed in biology laboratories when introducing microscopes and in astronomy when discussing telescopes. The Rayleigh criterion provides an expression for resolving power, where resolution is obtained when the minimum angular separation meets a specific threshold. In biology, a technique like using oil immersion can enhance resolving power by minimizing the refraction of light waves.