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The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall 3m away by means of a large convex lens. What is the maximum possible focal length of the lens required for the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A screen is placed 90cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 20cm. Determine the focal length of the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses. Determine the ‘effective focal length’ of the combination of the two

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20cm? An object 1.5 cm in size is placed on the side of the convex lens in the arrangement above. The distance between the object and

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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At what angle should a ray of light be incident on the face of a prism of refracting angle 60° so that it just suffers total internal reflection at the other face? The refractive index of the material of the prism is

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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You are given prisms made of crown glass and flint glass with a wide variety of angles. Suggest a combination of prisms which will deviate a pencil of white light without much

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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You are given prisms made of crown glass and flint glass with a wide variety of angles. Suggest a combination of prisms which will disperse (and displace) a pencil of white light without much

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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For a normal eye, the far point is at infinity and the near point of distinct vision is about 25cm in front of the eye. The cornea of the eye provides a converging power of about 40 dioptres, and the least converging power of the eye-lens behind the cornea is about 20 dioptres. From this rough data estimate the range of accommodation (i.e., the range of converging power of the eye-lens) of a normal

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Does short-sightedness (myopia) or long-sightedness (hypermetropia) imply necessarily that the eye has partially lost its ability of accommodation? If not, what might cause these defects of

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A myopic person has been using spectacles of power –1.0 dioptre for distant vision. During old age he also needs to use separate reading glass of power + 2.0 dioptres. Explain what may have

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A person looking at a person wearing a shirt with a pattern comprising vertical and horizontal lines is able to see the vertical lines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A man with normal near point (25 cm) reads a book with small print using a magnifying glass: a thin convex lens of focal length 5 cm. What is the closest and the farthest distance at which he should keep the lens from the page so that he can

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A man with normal near point (25 cm) reads a book with small print using a magnifying glass: a thin convex lens of focal length 5 cm. What is the maximum and the minimum angular magnification (magnifying power) possible using the above simple

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A card sheet divided into squares each of size 1 mm2 is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 9 cm) held close to the eye. What is the magnification produced by the lens? How much is the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A card sheet divided into squares each of size 1 mm2 is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 9 cm) held close to the eye. What should be the distance between the object and the magnifying

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Explain: The angle subtended at the eye by an object is equal to the angle subtended at the eye by the virtual image produced by a magnifying glass. In what sense then does a magnifying glass provide angular

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Explain: In viewing through a magnifying glass, one usually positions one’s eyes very close to the lens. Does angular magnification change if the eye is moved

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Explain: Magnifying power of a simple microscope is inversely proportional to the focal length of the lens. What then stops us from using a convex lens of smaller and smaller focal length and achieving greater and greater magnifying

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Explain: Why must both the objective and the eyepiece of a compound microscope have short focal

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Explain: When viewing through a compound microscope, our eyes should be positioned not on the eyepiece but a short distance away from it for best viewing. Why? How much should be that short distance between the eye and

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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