One of the inevitable consequences of aging is a decrease in the flexibility of the lens. This leads to the farsighted condition called presbyopia (elder eye). Almost every aging human will experience it to some extent. However, for the myopic, or nearsighted, person it is possible that far vision will be limited by a subpar far point and near vision will be hampered by an expanding near point. One solution is to wear bifocal lenses that are diverging in the upper half to correct the nearsightedness and converging in the lower half to correct the farsightedness. Suppose one such individual asks for your help. The patient complains that she can’t see far enough to safely drive (her far point dfar=109 cm) and she can’t read the font of her smart phone without holding it beyond arm’s length (her near point dnear=83.0 cm). Prescribe the bifocals that will correct the visual issues for your patient. For this question, you may ignore the distance between the lens and the eye. What is the focal length fns of the part of the bifocal lens that corrects the patient's nearsightedness? fns = ? cm What is the focal length ffs of the part of the bifocal lens that corrects the patient's farsightedness? ffs = ? cm
Ray Optics
Optics is the study of light in the field of physics. It refers to the study and properties of light. Optical phenomena can be classified into three categories: ray optics, wave optics, and quantum optics. Geometrical optics, also known as ray optics, is an optics model that explains light propagation using rays. In an optical device, a ray is a direction along which light energy is transmitted from one point to another. Geometric optics assumes that waves (rays) move in straight lines before they reach a surface. When a ray collides with a surface, it can bounce back (reflect) or bend (refract), but it continues in a straight line. The laws of reflection and refraction are the fundamental laws of geometrical optics. Light is an electromagnetic wave with a wavelength that falls within the visible spectrum.
Converging Lens
Converging lens, also known as a convex lens, is thinner at the upper and lower edges and thicker at the center. The edges are curved outwards. This lens can converge a beam of parallel rays of light that is coming from outside and focus it on a point on the other side of the lens.
Plano-Convex Lens
To understand the topic well we will first break down the name of the topic, ‘Plano Convex lens’ into three separate words and look at them individually.
Lateral Magnification
In very simple terms, the same object can be viewed in enlarged versions of itself, which we call magnification. To rephrase, magnification is the ability to enlarge the image of an object without physically altering its dimensions and structure. This process is mainly done to get an even more detailed view of the object by scaling up the image. A lot of daily life examples for this can be the use of magnifying glasses, projectors, and microscopes in laboratories. This plays a vital role in the fields of research and development and to some extent even our daily lives; our daily activity of magnifying images and texts on our mobile screen for a better look is nothing other than magnification.
One of the inevitable consequences of aging is a decrease in the flexibility of the lens. This leads to the farsighted condition called presbyopia (elder eye). Almost every aging human will experience it to some extent. However, for the myopic, or nearsighted, person it is possible that far vision will be limited by a subpar far point and near vision will be hampered by an expanding near point. One solution is to wear bifocal lenses that are diverging in the upper half to correct the nearsightedness and converging in the lower half to correct the farsightedness.
Suppose one such individual asks for your help. The patient complains that she can’t see far enough to safely drive (her far point dfar=109 cm) and she can’t read the font of her smart phone without holding it beyond arm’s length (her near point dnear=83.0 cm). Prescribe the bifocals that will correct the visual issues for your patient. For this question, you may ignore the distance between the lens and the eye.
What is the focal length fns of the part of the bifocal lens that corrects the patient's nearsightedness?
fns = ? cm
What is the focal length ffs of the part of the bifocal lens that corrects the patient's farsightedness?
ffs = ? cm
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