The power of a lens of focal length 20 cm is:enerated by:
Correct answer: B. 5 diopters
- A. 20 diopters
- B. 5 diopters
- C. 1/20 diopters
- D. 1/5 diopters
Explanation
The correct option is B because The power of a lens in diopters is defined as the reciprocal of its focal length in meters. Therefore, a lens with a focal length of 20 cm (or 0.2 meters) has a power of 1/0.2 = 5 diopters.
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Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
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