Most animals—humans included—have eyes that use lenses to form images. The eyes of scallops are different. A typical scallop eye forms images largely by reflection from a mirror- like surface at the back of the eye. as shown the important features of a typical scallop eye. The lens causes very little redirection of incoming light rays; it is the spherical surface in the back of the eye that brings rays of light to a focus on the cells of the retina. (For simplicity, we’ve shown no refraction by the lens, although the lens does cause some refraction that seems to help to make the image sharper by correcting for the spherical aberration introduced by the mirror.) The reflection is due to thin-film interference from the front and back faces of 80-nm-thick transparent crystals of guanine, index n = 1.83, that are embedded in cytoplasm with index n = 1.34. The individualeyes are quite small. A typical scallop has 40 to 60 eyes, each with a 450-mm–diameter pupil and a reflecting surface at the back of the eye with a focal length of only 200 mm. The unusual imaging system of the scallop eye makes it very sensitive to light. The ratio of the focal length to the aperture of an optical system is known as the f-number. A smaller f-number implies greater light sensitivity. A telescope optimized for light gathering might have an f-number of 4; the scallop’s f-number of less than 0.5 means that its small eyes work well in very dim light. For the typical pupil diameter of 3.0 mm, what is the approximate f-number for a human eye?A. 2B. 4C. 6D. 8
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.
Most animals—humans included—have eyes that use lenses to form images. The eyes of scallops are different. A typical scallop eye forms images largely by reflection from a mirror- like surface at the back of the eye. as shown the important features of a typical scallop eye. The lens causes very little redirection of incoming light rays; it is the spherical surface in the back of the eye that brings rays of light to a focus on the cells of the retina. (For simplicity, we’ve shown no refraction by the lens, although the lens does cause some refraction that seems to help to make the image sharper by correcting for the spherical aberration introduced by the mirror.) The reflection is due to thin-film interference from the front and back faces of 80-nm-thick transparent crystals of guanine, index n = 1.83, that are embedded in cytoplasm with index n = 1.34. The individual
eyes are quite small. A typical scallop has 40 to 60 eyes, each with a 450-mm–diameter pupil and a reflecting surface at the back of the eye with a focal length of only 200 mm. The unusual imaging system of the scallop eye makes it very sensitive to light. The ratio of the focal length to the aperture of an optical system is known as the f-number. A smaller f-number implies greater light sensitivity. A telescope optimized for light gathering might have an f-number of 4; the scallop’s f-number of less than 0.5 means that its small eyes work well in very dim light.
For the typical pupil diameter of 3.0 mm, what is the approximate f-number for a human eye?
A. 2
B. 4
C. 6
D. 8
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