Optics 2025 – 400 Free Practice Questions to Pass the Exam

Optical power is expressed in diopters, which is the correct answer. This unit specifically measures the refractive power of lenses. The diopter is defined as the reciprocal of the focal length of the lens in meters. For instance, a lens with a focal length of 1 meter has a power of 1 diopter, while a lens with a focal length of 0.5 meters has a power of 2 diopters.

In the context of optics, diopters are particularly significant because they directly relate to how strongly a lens converges or diverges light. The concept of optical power in diopters helps optical technicians and professionals to design and evaluate lenses quickly and efficiently.

Other units mentioned, such as watts, volts, and pascals, are not used to measure optical power. Watts pertain to electrical power, volts measure electric potential, and pascals are units of pressure. These units belong to different physical quantities and do not convey information about the refractive characteristics of lenses. Thus, diopters is the only unit among the options listed that accurately represents optical power.