NEET Physics Refraction at Curved Surface Lenses and Power of Lens MCQs Set A

a) divergent lens

b) homogeneous liquid

c) convergent lens

d) plane glass

Answer: divergent lens

Question:  A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The distance of the virtual image from the surface of the sphere is

a) 6 cm

b) 12 cm

c) 4 cm

d) 2 cm

Answer: 6 cm

Question: A planoconvex lens of focal length 16 cm, is to be made of glass of refractive index 1.5. The radius of curvature of the curved surface should be

a) 8 cm

b) 12 cm

c) 16 cm

d) 24 cm

Answer: 8 cm

Question: Two thin lenses are in contact and the focal length of the combination is 80 cm. If the focal length of one lens is 20 cm, then the power of the other lens will be

a) – 3.75 D

b) – 100 D

c) 1.66 D

d) 4.00 D

Answer: – 3.75 D

Question: A plano-convex lens is made of material of refractive index 1.6. The radius of curvature of the curved surface is 60 cm. The focal length of the lens is

a) 100 cm

b) 50 cm

c) 200 cm

d) 400 cm

Answer:  100 cm

Question:  A parallel beam of light is incident on the surface of a transparent hemisphere of radius R and refractive index 2.0 as shown in figure. The position of the image formed byrefraction at the first surface is :

a) 2R

b) 3R

c) R

d) R/2

Answer: 2R

Question: A lens made of glass whose index of refraction is 1.60 has a focal length of + 20 cm in air. Its focal length in water, whose refractive index is 1.33, will be

a) three times longer than in air

b) two times longer than in air

c) same as in air

d) None of these

Answer: three times longer than in air

Question:  A convex lens is in contact with concave lens. The magnitude of the ratio of their powers is 2/3. Their equivalent focal length is 30 cm. What are their individual focal lengths (in cm)?

a) –15, 10

b) –10, 15

c) 75, 50

d) –75, 50

Answer: –15, 10

More Questions.....................................

Question:  A bi-convex lens made of glass (refractive index 1.5) is put in a liquid of refractive index 1.7. Its focal length will

a) increase and change sign

b) decrease and remain of the same sign

c) increase and remain of the same sign

d) decrease and change sign

Answer: increase and change sign

Question:   If two + 5 diopter lenses are mounted at some distance apart, the equivalent power will always be negative if the distance is

a) greater than 40 cm

b) equal to 40 cm

c) less than 10 cm

d) equal to 10 cm

Answer: greater than 40 cm

Question:  The rays of different colours fail to converge at a point after going through a converging lens. This defect is called

a) chromatic aberration

b) distortion

c) spherical aberration

d) coma

Answer:  chromatic aberration

Question:  What causes chromatic aberration?

a) Variation of focal length of lens with colour

b) Central rays

c) Difference in radii of curvature of its surfaces

d) Marginal rays

Answer: Variation of focal length of lens with colour

Question: A convex lens is made of 3 layers of glass of 3 different materials as in the figure. A point object is placed on its axis. The number of images of the object are

a) 1

b) 2

c) 3

d) 4

Answer:  1

Question:  Two point source S₁ and S₂ are 24 cm apart. Where should a convex lens of focal length 9 cm be placed in between them so that the images of both sources are formed at the same place?

a) 6 cm from S₁

b) 10 cm from S₁

c) 15 cm from S₁

d) None of these

Answer: 6 cm from S₁

Question: A parallel beam of light is incident on a converging lens parallel to its principal axis. As one moves away from the lens on the other side on its principal axis, the intensity of light

a) remains constant

b) continuously increases

c) continuously decreases

d) first increases then decreases

Answer:  remains constant