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(i) How is the focal length of a spherical mirror affected when it is immersed in water? (ii) A convex lens has 10 cm focal length in air. What is its focal length in water? (Refractive index of air-water = 1.33, refractive index of air-glass =

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

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An object of 3 cm height is placed at a distance of 60 cm from a convex mirror of focal length 30 cm. Find the nature, position and size of the image

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

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(i) Draw a labelled ray diagram showing the formation of a final image by a compound microscope at least distance of distinct vision. (ii) The total magnification produced by a compound microscope is 20. The magnification produced by the eyepiece is 5. The microscope is focused on a certain object. The distance between the objective and eyepiece is observed to be 14 cm. If least distance of distinct vision is 20 cm. Calculate the focal length of the objective and the

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

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You are given four sources of light each one providing a light of a single colour – red, blue, green and yellow. Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is 90°. Which of the following statements is correct if the source of yellow light is replaced with that of other lights without changing the angle of

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

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A car is moving with at a constant speed of 60 km h–1 on a straight road. Looking at the rear view mirror, the driver finds that the car following him is at a distance of 100 m and is approaching with a speed of 5 km h –1. In order to keep track of the car in the rear, the driver begins to glance alternatively at the rear and side mirror of his car after every 2 s till the other car overtakes. If the two cars were maintaining their speeds, which of the following statement (s) is/are

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

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A gravitational lens may be assumed to have a varying width of the form Show that an observer will see an image of a point object as aring about the center of the lens with an angular radius`W(b)=k_1` ln `k_2/b`

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

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A beam of light consisting of two wavelengths, 650 nm and 520 nm, is used to obtain interference fringes in a Young’s double-slit experiment. What is the least distance from the central maximum where the bright fringes due to both the wavelengths

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

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For sound waves, the Doppler formula for frequency shift differs slightly between the two situations: (i) source at rest; observer moving, and (ii) source moving; observer at rest. The exact Doppler formulas for the case of light waves in vacuum are, however, strictly identical for these situations. Explain why this should be so. Would you expect the formulas to be strictly identical for the two situations in case of light travelling in a

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

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Answer the following questions: In what way is diffraction from each slit related to the interference pattern in a double-slit

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

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Define a wavefront. Use Huygens' geometrical construction to show the propagation of plane wavefront from a rarer medium (1) to a denser medium (2) undergoing refraction, hence derive Snell's law of

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

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A beam of light consisting of two wavelengths 560 nm and 420 nm is used to obtain interference fringes in a Young's double slit experiment. Find the least distance from the central maximum, where the bright fringes, due to both the wavelengths coincide. The distance between the two slits is 4.0 mm and the screen is at a distance of 1.0 m from the

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

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State clearly how an unpolarised light get linearly polarised, when passed through a polaroid. (i) Unpolarised light of intensity `I_0` is incident on a polaroid `P_1` which is kept near polaroid `P_2` whose pass axis is parallel to that of `P_1`. How will the intensities of light, `I_1 and I_2` transmitted by the polaroids `P_1 and P_2` respectively, change on rotating `P_1` without disturbing `P_2` ? (ii) Write the relation between the intensities `I_1 and

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

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In the above question what is the intensity of light at P if light from `S_1` and `S_2` is same i.e. (I) units. Consider these sources are

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

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For what kinetic energy of a neutron will the associated de Broglie wavelength be 1.40 × 10–10

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

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The wavelength of a probe is roughly a measure of the size of a structure that it can probe in some detail. The quark structure of protons and neutrons appears at the minute length-scale of 10–15 m or less. This structure was first probed in early 1970’s using high energy electron beams produced by a linear accelerator at Stanford, USA. Guess what might have been the order of energy of these electron beams. (Rest mass energy of electron = 0.511

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

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Find the typical de Broglie wavelength associated with a He atom in helium gas at room temperature (27 °C) and 1 atm pressure; and compare it with the mean separation between two atoms under these

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

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Consider a thin target (10–2m square, 10–3m thickness) of sodium, which produces a photocurrent of 100μA when a light of intensity 100W/m2 (λ = 660nm) falls on it. Find the probability that a photoelectron is produced when a photons strikes a sodium atom. [Take density of Na = 0.97

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

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Show graphically how the stopping potential for a given photosensitive surface varies with the frequency of incident

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

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By how much would the stopping potential for a given photosensitive surface goup if the frequency of the incident radiations were to be increased from `4×10^(15) Hz` to `8 × 10^(15) Hz? ` `(h=6.4xx10^(-3)4Js,

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

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Electric charge is uniformly distributed on the surface of a spherical balloon. Show how electric intensity and electric potential vary (a) on the surface (b) inside and (c)

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

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