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(i) Why does the sun appear reddish at sunset or sunrise? (ii) For which colour, the refractive index of prism material is maximum and

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

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Find the radius of curvature of the convex surface of a plano-convex lens, whose focal length is 0.3 m and the refractive index of the material of the lens is 1 .5

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

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(i) Out of blue and red light, which is deviated more by a prism? Give reason. (ii) Give the formula that can be used to determine refractive index of material of a prism in minimum deviation

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

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The following table gives the values of the angle of deviation for different values of the angle of incidence for a triangular prism. Angle of incidence 33° 38° 42° 52° `60^o` 71° Angle of deviation O') `60^o` 50° 46° `40^o` 43° 50° (i) For what value of the angle of incidence, is the angle of emergence likely to be equal to the angle of incidence itself? (ii) Draw a ray diagram showing the passage of a ray of light through this prism when the angle of incidence has the above

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

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(i) State the principle on which the working of an optical fibre is based. (ii) What are the necessary conditions for this phenomenon to

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

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(i) What is the relation between critical angle and refractive index of a material? (ii) Does critical angle depend on the colour of light?

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

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(i) A mobile phone lies along the I principal axis of a concave mirror. Show with the help of a suitable diagram, the formation of its image. Explain whymagnification is not a uniform, (ii) Suppose the lower half of the concave mirror's reflecting surface is covered with an opaque material. What effect this will have on the image of the object?

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

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A convex lens of focal length 30 cm is placed coaxially with a convex mirror of radius of curvature 20 cm. The two are kept at 15 cm from each other. A point object lies 60 cm in front of the convex lens. Draw a ray diagram to show the formation of the image by the combination. Determine the nature and position of the image

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

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A convex lens of focal length 20 cm is placed coaxially with a concave mirror of focal length 10 cm at a distance of 50 cm apart from each other. A beam of light coming parallel to the principal axis is incident on the convex lens. Find the position of the final image formed by this combination. Draw the ray diagram showing the formation of the

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

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Define power of a lens. Write its units. Deduce the relation `1/f=1/f_1+1/f_2` for two thin lenses kept in contact

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

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You are given three lenses `L_1,L_2 and L_3` each of focal length 10 cm. An object is kept at 15 cm in front of `L_1` as shown. The final real image is formed at the focus `I` of `L_3` . Find the separation between `L_1, L_2 and

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

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A convex lens made up of a glass of refractive index 1.5 is dipped in turn in (i) a medium of refractive index 1.65 (ii) a medium of refractive index 1.33 (a) Will it behave as a converging lens or a diverging lens in the two cases? (b) How will its focal length change in the two

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

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Use the mirror equation to show that (i) An object placed between `f` and `2f` of a concave mirror produces a real image beyond `2f`. (ii) A convex mirror always produces a virtual image independent of the location of the object. (iii) An object placed between the pole and focus of a concave mirror produces a virtual and enlarged

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

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A converging lens has a focal length of 20 cm in air. It is made of a material of refractive index 1.6. It is immersed in a liquid of refractive index 1.3. Calculate its new focal

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

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Find the position of the image formed of the object O by the lens combination given in the

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

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State the necessary conditions for producing total internal reflection of light. Draw ray diagrams to show how specially designed prisms make use of total internal reflection to obtain inverted image of the object by deviation of rays (i) through 90° and (ii) through

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

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With the help of a suitable ray diagram, derive a relation between the object distance (u), image distance (v) and radius of curvature R for the convex spherical surface when a ray of light travels from a rarer to denser

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

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A ray of light is incident on one face of a glass prism and emerges out from the other face. Trace the path of the ray and derive an expression for refractive index of the glass

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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A convex lens is used to obtain a magnified image of an object on a screen 10 cm from the lens. If the magnification is 19, find the focal length of the

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

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