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Light from a point source in air falls on a spherical glass surface (n = 1.5 and radius of curvature = 20 cm). The distance of the light source from the glass surface is 100 cm. At what position the image is

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

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A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the

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Use the mirror equation to deduce that: the virtual image produced by a convex mirror is always diminished in size and is located between the focus and the

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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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A small telescope has an objective lens of focal length 140cm and an eyepiece of focal length 5.0cm. What is the magnifying power of the telescope for viewing distant objects when the telescope is in normal adjustment (i.e., when the final image is at infinity)?(ii) the final image is

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

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For the same value of angle of y incidence, the angles of refraction in three media A, B and C are 15°, 25° and 35° respectively. In which medium, would the velocity of light be

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

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(i) The bluish colour predominates in clear sky. (ii) Violet colour is seen at the bottom of the spectrum when , white light is dispersed by a prism. State reasons to explain these

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

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The image obtained with a convex lens is erect and its length is four times the length of the object. If the focal length of the lens is 20 cm, calculate the object and image

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

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(i) Draw a neat labelled ray diagram of a compound microscope. Explain briefly its working. (ii) 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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How is the working of a telescope different from that of a microscope? The focal lengths of the objective and eyepiece of a microscope are 1.25 cm and 5 cm, respectively. Find the position of the object relative to the objective in order to obtain an angular magnification of 30 in normal

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

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Draw the labelled ray diagram for the formation of image by an astronomical telescope. Derive the expression for its magnifying power in normal adjustment. Write two basic features which can distinguish between a telescope and a Compound

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

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In many experimental set-ups the source and screen are fixed at a distance say D and the lens is movable. Show that there are two positions for the lens for which an image is formed on the screen. Find the distance between these points and the ratio of the image sizes for these two

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

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Estimate the distance for which ray optics is good approximation for an aperture of 4 mm and wavelength 400

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

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Answer the following questions: When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the shadow of the obstacle. Explain

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

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The intensity at the central maxima `(O)` in a Young's double slit experiment is `I_0` . If the distance OP equals one-third of fringe width of the pattern, then show that the intensity at point P would be `I_0

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

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In Young's double slit experiment, the two slits 0.15 mm apart are illuminated by monochromatic light of wavelength 450 nm. The screen is 1.0 m away from the slits. (i) Find the distance of the second (a) bright fringe(b) dark fringe from the central maximum. (ii) How will the fringe pattern change if the screen is moved away from the

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

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In Young's double slit experiment, monochromatic light of wavelength 630 nm illuminates the pair of slits and produces an interference pattern in which two consecutive bright fringes are separated by 8.1 mm . Another source of monochromatic light produces the interference pattern in which the two consecutive bright fringes are separated by 7.2 mm. Find the wavelength of light from the second source. What is the effect on the interference fringes, is when monochromatic source is replaced by a source of white

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

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The threshold frequency for a certain metal is 3.3 × 1014 Hz. If light of frequency 8.2 × 1014 Hz is incident on the metal, predict the cutoff voltage for the photoelectric

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

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What is the(a) momentum, (b) speed, (c) de Broglie wavelength of an electron with kinetic energy of 120

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

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An electron microscope uses electrons accelerated by a voltage of 50 kV. Determine the de Broglie wavelength associated with the electrons. If other factors (such as numerical aperture, etc.) are taken to be roughly the same, how does the resolving power of an electron microscope compare with that of an optical microscope which uses yellow

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

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