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(i) How is the focal length of a spherical mirror affected when the wavelength of the light used is increased? (ii) A convex lens has 20 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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(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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An object of 2 cm height is placed at a distance of 30 cm from a convex mirror of focal length 15 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) With the help of a suitable ray diagram, derive the mirror formula for a concave mirror. (ii) The near point of a hypermetropic person is 50 cm from the eye. What is the power of the lens required to enable the person to read clearly a book held at 25 cm from the

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

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Three light rays, red (R) green (G) and blue (B) are incident on a right angled prism AB C at face AB. The , refractive indices of the material of the prism for red, green and blue wavelengths are 1.39, 1.44 and 1.47 respectively. Out of the three, which colour of ray will emerge out of face AC? Justify your answer. Trace the path of these rays after passing through face

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

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State the conditions under which total internal reflection occurs. One face of a prism with a refracting angle of 30° is coated with silver. A rayincident on another face at an angle of 45° is refracted and reflected from the silver coated face and retraces its path. Find the refractive index of the material of the

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

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A tank is filled with water to a height of 12.4 cm. The apparent depth of a needle lying at the bottom of the tank is measured by a microscope to be 9.3 cm. What is the refractive index of water? If water is replaced by a liquid of refractive index 1 .6 up to the same height, by what distance would the microscope have to be moved to focus on the needle

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

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The velocity of a certain monochromatic light in a given transparent medium is `2.225 xx10^8` m/s. What is the (i) critical angle of incidence (ii) polarising angle for this

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

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When a ray of light passes through a triangular glass prism, find out the relation for the total deviation, `delta` in terms of the angle of incidence, i and angle of emergence, e. Plot a graph showing the variation of angle of deviation with the angle of incidence and obtain the condition for the angle of minimum

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Light incident at an angle of incidence of 45° in a certain medium goes grazing along its surface of separation from air after refraction. What is (i) the velocity of light in this medium? (ii) the angle of incidence at which light from air must be incident on this medium so that the refracted ray is normal to the reflected ray? Also, name the special property exhibited by light for this angle of

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

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One day Chetan's mother developed a severe stomach ache all of a sudden. She was rushed to the doctor who suggested for an immediate endoscopy test and gave an estimate of expenditure for the same. Chetan immediately contacted his class teacher and shared the information with her. The class teacher arranged for the money and rushed to the hospital. On realising that Chetan belonged to a below average income group family, even the doctor offered concession for the test fee. The test was conducted successfully. Answer the following questions based on the above information. (i) Which principle in optics is

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

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(i) A point object O is kept in a medium of refractive index in front of a convex spherical surface of radius of curvature R which separates the second medium of refractive index `n_2` from the first one, as shown in the figure.Draw the ray diagram showing the image formation and deduce the relationship between the object distance and the image distance in terms of `n_1 , n_2 and R`.(ii) When the image formed above acts as a virtual object for a concave spherical surface separating the medium `n_2` from `n_1(n_2 > n_1)` , draw this ray diagram and write

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

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(i) A ray PQ of light is incident on the face AB of a glass prism ABC (as shown in the figure) and emerges out of the face AC. Trace the path of the ray. Show that `/_i+/_e=/_A+/_delta` where, `delta` and e denote the angle of deviation and angle of emergence respectively. Plot a graph showing the variation of the angle of deviation as a function of angle of incidence. State the condition under which `/_delta` is minimum. (ii) Find out the relation between the refractive index `(mu)` of the glass prism and `/_A` for the case, when the angle

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

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(i) A point object is placed in front of a double convex lens (or refractive index `mu=n_2/n_1` with respect to air) with its spherical faces of radii of curvature `R_1 and R_2` Show the path of rays due to refraction at first and subsequently at the second surface to obtain the formation of the real image of the object. Hence, obtain the lens maker's formula for a thin lens. (ii) A double convex lens having both faces of the same radius of curvature has refractive index 1.55. Find out the radius of curvature of the lens required to get the

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

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Draw a ray diagram showing the formation of the image by a point object on the principal axis of a spherical convex surface separating two media of refractive indices `n_1 and n_2`, when a point source is kept in rarer medium of refractive index `n_1`. Derive the relation between object and image distance in terms of refractive index of the medium and radius of curvature of the surface. Hence, obtain the expression for lens maker's formula in the case of thin convex

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

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(i) Draw a ray diagram to show refraction of a ray of monochromatic light passing through a glass prism. Deduce the expression for the refractive index of glass in terms of angle of prism and angle of minimum deviation, (ii) Explain briefly how the phenomenon of total internal reflection is used in fibre

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

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(i) Obtain lens maker's formula using the expression`n_2/v-n_1/u=((n_2-n_1))/R`Here, the ray of light propagating from a rarer medium of refractive index `(n_1)` to a denser medium of refractive index `(n_2)` is incident on the convex side of spherical refracting surface of radius of curvature R. (ii) Draw a ray diagram to show that image formation by a concave mirror when the object is kept between its focus and the pole. Using this diagram, derive the magnification formula for the image

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

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(i) Figure shows a convex spherical surface with centre of curvature C separating the two media of refractive indices `n_1 and n_2`. Draw a ray diagram showing the formation of the image of a point object O lying on the principal axis. Derive the relationship between the object and image distance in terms of refractive indices of the media and the radius of curvature R of the surface. (ii) Define the magnifying power of a compound microscope. Why should both the objective and the eyepiece have small focal lengths in a

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

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Trace the rays of light showing the formation of an image due to a point object placed on the axis of a spherical surface separating the two media of refractive indices `n_1 and n_2`. Establish the relation between the distance of the object, the distance of image and the radius of curvature from the central point of the spherical surface. Hence, derive the expression of the lens maker's

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

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