Ray Optics and Optical Instruments

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the most appropriate answer from the options given below:

1. Both (A) and (R) are correct and (R) is the correct explanation of (A)
2. (A) is correct but (R) is not correct
3. (A) is not correct but (R) is correct
4. Both (A) and (R) are correct but (R) is not the correct explanation of (A)

A mirror is used to produce an image with magnification of 14. If the distance between object and its image is 40 cm, then the focal length of the mirror is .

1. 10 cm
2. 12.7 cm
3. 10.7 cm
4. 15 cm

A transparent block A having refractive index = 1.25 is surrounded by another medium of refractive index = 1.0 as shown in the figure. A light ray is incident on the flat face of the block with incident angle as shown in the figure. What is the maximum value of for which light suffers total internal reflection at the top surface of the block? [figure]

1. -1(4/3)
2. -1(3/4)
3. -1(3/4)
4. -1(3/4)

When an object is placed 40 cm away from a spherical mirror an image of magnification 12 is produced. To obtain an image with magnification of 13, the object is to be moved :

1. 20 cm away from the mirror.
2. 20 cm towards the mirror.
3. 80 cm away from the mirror.
4. 40 cm away from the mirror.

A finite size object is placed normal to the principal axis at a distance of 30 cm from a convex mirror of focal length 30 cm. A plane mirror is now placed in such a way that the image produced by both the mirrors coincide with each other. The distance between the two mirrors is :

1. 45 cm
2. 15 cm
3. 22.5 cm
4. 7.5 cm

Consider following statements for refraction of light through prism, when angle of deviation is minimum. Choose the correct answer from the options given below :

1. A, B and E Only
2. B, C and D Only
3. B, D and E Only
4. A, C and D Only

The radii of curvature for a thin convex lens are 10 cm and 15 cm respectively. The focal length of the lens is 12 cm. The refractive index of the lens material is

1. 1.4
2. 1.8
3. 1.5
4. 1.2

A monochromatic light of frequency 5 1014 Hz travelling through air, is incident on a medium of refractive index '2'. Wavelength of the refracted light will be:

1. 400 nm
2. 300 nm
3. 600 nm
4. 500 nm

[figure] A spherical surface separates two media of refractive indices 1 and 1.5 as shown in figure. Distance of the image of an object 'O', is : (C is the center of curvature of the spherical surface and R is the radius of curvature)

1. 0.24 m left to the spherical surface
2. 0.24 m right to the spherical surface
3. 0.4 m left to the spherical surface
4. 0.4 m right to the spherical surface

A slanted object AB is placed on one side of convex lens as shown in the diagram. The image is formed on the opposite side. Angle made by the image with principal axis is : [figure]

1. -
2. - 2
3. -45
4. +45

Two identical objects are placed in front of convex mirror and concave mirror having same radii of curvature of 12 cm, at same distance of 18 cm from the respective mirrors. The ratio of sizes of the images formed by convex mirror and by concave mirror is :

1. 2
2. 1/2
3. 1/3
4. 3

A bi-convex lens has radius of curvature of both the surfaces same as 1/6 cm. If this lens is required to be replaced by another convex lens having different radii of curvature on both sides (R1 R2), without any change in lens power then possible combination of R1 and R2 is :

1. 13 cm and 17 cm
2. 15 cm and 17 cm
3. 13 cm and 13 cm
4. 16 cm and 19 cm

Let u and v be the distances of the object and the image from a lens of focal length f. The correct graphical representation of u and v for a convex lens when |u| > f, is

1. [figure]
2. [figure]
3. [figure]
4. [figure]

At the interface between two materials having refractive indices n1 and n2, the critical angle for reflection of an em wave is 1C. The n2 material is replaced by another material having refractive index n3 such that the critical angle at the interface between n1 and n3 materials is 2C. If n3 > n2 > n1; n2n3 = 25 and 2C - 1C = 12, then 1C is :

1. -1 ( 16n1 )
2. -1 ( 13n1 )
3. -1 ( 56n1 )
4. -1 ( 23n1 )

A thin prism P1 with angle 4 made of glass having refractive index 1.54, is combined with another thin prism P2 made of glass having refractive index 1.72 to get dispersion without deviation. The angle of the prism P2 in degrees is

1. 1.5
2. 16/3
3. 3
4. 4

A hemispherical vessel is completely filled with a liquid of refractive index . A small coin is kept at the lowest point (O) of the vessel as shown in figure. The minimum value of the refractive index of the liquid so that a person can see the coin from point E (at the level of the vessel) is . [figure]

1. 32
2. 32
3. 3
4. 2

A concave mirror produces an image of an object such that the distance between the object and image is 20 cm. If the magnification of the image is -3, then the magnitude of the radius of curvature of the mirror is :

1. 3.75 cm
2. 15 cm
3. 7.5 cm
4. 30 cm

In a long glass tube, mixture of two liquids A and B with refractive indices 1.3 and 1.4 respectively, forms a convex refractive meniscus towards A. If an object placed at 13 cm from the vertex of the meniscus in A forms an image with a magnification of -2, then the radius of curvature of meniscus is :

1. 23 cm
2. 43 cm
3. 13 cm
4. 1 cm