Explore the complete Optics of Lenses MCQ and Ophthalmic Instruments MCQs (Q41–80) with answers reference on A.K. Khurana. Covers lenses, mirrors and image formation, focal length, magnification, sign conventions and ophthalmic optics concepts for optometry students and NEET PG, AIIMS Optometry exam preparation. Get a complete ophthalmic study guide and ophthalmic technician notes for exam revision. Optometry and Ophthalmology MCQ
Optics of Lenses MCQ
Q41. A convex lens is also called a ______ lens.
A. Diverging B. Converging C. Neutral D. Plano
View Answer
B. Converging Exp: Convex lens brings parallel rays to a focus.
Q42. A concave lens is also known as a ______ lens.
A. Converging B. Diverging C. Neutral D. Cylindrical
View Answer
B. Diverging Exp: Concave lens spreads parallel rays apart.
Q43. For a biconvex lens, both radii of curvature are:
A. Equal and positive
B. Equal but opposite in sign
C. Different and positive
D. Zero
View Answer
B. Equal but opposite in sign ✅ Exp: According to sign convention, radii on opposite sides have opposite signs.
Q44. Principal axis of a lens passes through:
A. Optical center
B. Vertex
C. Focal point only
D. Nodal point
View Answer
A. Optical center ✅ Exp: Principal axis is the line joining centers of curvature through the optical center.
Q45. The point where light rays pass undeviated through a lens is called the:
A. Nodal point
B. Principal focus
C. Optical center
D. Secondary axis
View Answer
C. Optical center ✅ Exp: Rays passing through the optical center are undeviated.
Q46. The distance between the optical center and principal focus is called:
A. Focal length
B. Radius of curvature
C. Axial length
D. Vergence
View Answer
A. Focal length ✅ Exp: Focal length determines the power of a lens.
Q47. For a +2 D lens, the focal length equals:
A. 50 cm B. 25 cm C. 33 cm D. 100 cm
View Answer
A. 50 cm ✅
Q48. For a –4 D lens, the focal length is:
A. –25 cm B. 25 cm C. –50 cm D. 50 cm
View Answer
A. –25 cm Exp: Negative sign indicates virtual focus on the same side as the object.
Q49. When object is placed at 2F in front of a convex lens, image forms at:
A. F
B. Between F and 2F
C. At 2F on opposite side
D. Infinity
View Answer
C. At 2F on opposite side ✅ Exp: Image same size, real and inverted.
Q50. When object is placed between F and optical center of a convex lens, image is:
A. Real, inverted, diminished
B. Virtual, erect, magnified
C. Real and same size
D. Virtual, inverted
View Answer
B. Virtual, erect, magnified ✅ Exp: Magnifying lens effect.
Optics of Lenses MCQ
Q51. Concave lens always forms:
A. Real image
B. Virtual erect diminished image
C. Real magnified
D. Inverted
View Answer
B. Virtual erect diminished image ✅ Exp: Diverges rays so image appears on same side as object.
Q52. Image formed by concave lens is always located:
A. On the opposite side of object
B. On same side as object
C. At focal point
D. At infinity
View Answer
B. On same side as object ✅ Exp: Virtual image appears between lens and focal point.
Q53. Magnification (m) = image height/object height = also equals:
A. v/u B. u/v C. –u/v D. 1/f
View Answer
A. v/u Exp: m = v/u (considering sign conventions).
Q54. In concave lens, magnification is:
A. > 1
B. < 1
C. = 1
D. Variable
View Answer
B. < 1 Exp: Image always smaller than object.
Optics of Lenses MCQ
Q55. In convex lens, magnification > 1 when:
A. Object inside F B. Object at 2F C. Object beyond 2F D. Object at F
View Answer
A. Object inside F Exp: Object between F and O produces magnified virtual image.
Q56. The formula relating object and image distance to focal length is:
A. u + v = f
B. 1/f = 1/v + 1/u
C. uv = f
D. f = u – v
View Answer
B. 1/f = 1/v + 1/u ✅ Exp: Lens formula for thin lenses.
Q57. If u = 30 cm, f = 15 cm, find v.
A. +30 cm B. –30 cm C. +15 cm D. +10 cm
View Answer
A. +30 cm Exp: 1/f = 1/v + 1/u → 1/15 = 1/v + 1/30 → v = 30 cm.
Q58. A real image by a lens implies that:
A. Image is erect
B. Image can be projected on a screen
C. It lies behind the lens
D. None
View Answer
B. Image can be projected on a screen ✅ Exp: Real images can be formed on a surface.
Q59. A virtual image is:
A. Erect B. Inverted C. Real D. Reversed
View Answer
A. Erect Exp: Virtual images are always erect.
Q60. Sign convention: All distances measured opposite to incident light are considered:
A. Positive
B. Negative
C. Zero
D. Variable
View Answer
B. Negative ✅ Exp: Cartesian sign convention in optics.
Optics of Lenses MCQ
Q61. A concave mirror is a ______ mirror.
A. Converging B. Diverging C. Plane D. Neutral
View Answer
A. Converging Exp: Reflects light inward to a focus.
Q62. A convex mirror is a ______ mirror.
A. Converging B. Diverging C. Plane D. Neutral
View answer
B. Diverging ✅ Exp: Spreads reflected rays outward.
Q63. Focal length of a spherical mirror =
A. R/2 B. R C. 2R D. R³
View Answer
A. R/2 ✅ Exp: for spherical mirrors.
Q64. Mirror formula is:
A. 1/f = 1/u + 1/v
B. f = u + v
C. uv = f²
D. f = 1/u – 1/v
View Answer
A. 1/f = 1/u + 1/v ✅ Exp: Same form as lens equation.
Q65. Convex mirror always forms:
A. Real and inverted
B. Virtual and erect
C. Real and magnified
D. Inverted and diminished
View Answer
B. Virtual and erect ✅ Exp: Acts as a diverging mirror.
Optics of Lenses MCQ
Q66. Plane mirror forms image that is:
A. Real, inverted
B. Virtual, erect, same size
C. Virtual, diminished
D. Inverted
View Answer
B. Virtual, erect, same size ✅ Exp: Image same size and distance behind mirror.
Q67. If an object is placed at center of curvature of concave mirror, image is:
A. At focus
B. At C
C. Between F and C
D. At infinity
View Answer
B. At C ✅ Exp: Equal size, real, and inverted.
Q68. Magnification by mirror =
A. v/u B. u/v C. 1/f D. f/u
View Answer
A. v/u Exp: Ratio of image to object distance.
Q69. In a concave mirror, if object is between F and mirror, image is:
A. Virtual and magnified B. Real and inverted C. Real and same size D. Virtual and diminished
View Answer
A. Virtual and magnified ✅ Exp: Used in make-up mirrors and dentistry.
Q70. Convex mirror has focal length:
A. Positive
B. Negative
C. Zero
D. Infinity
View Answer
B. Negative ✅ Exp: By sign convention, focus behind mirror → negative.
Q71. Lateral magnification > 1 means image is:
A. Magnified B. Reduced C. Same size D. Inverted
View Answer
A. Magnified ✅ Exp: Image size > object size.
Q72. A concave mirror used in ophthalmoscope helps:
A. Condense light into the pupil B. Diffuse light C. Absorb light D. Magnify image
View Answer
A. Condense light into the pupil ✅ Exp: Concave mirror collects light into narrow beam.
Q73. When rays strike a mirror normally, angle of incidence is:
A. 0° B. 45° C. 90° D. 180°
View Answer
A. 0° ✅ Exp: Normal incidence → zero angle → back reflection.
Q74. In ophthalmic mirrors, silvered surface is kept:
A. Behind glass plate
B. In front
C. Middle
D. Polished both sides
View Answer
B. In front ✅ Exp: Front-silvering avoids ghost reflections.
Q75. Refractive index of human lens ≈
A. 1.33 B. 1.41 C. 1.376 D. 1.50
View Answer
B. 1.41 ✅ Exp: Gradient index averages around 1.41.
Q76. If a lens forms a real image twice the size of object, object distance = ?
A. 3f B. 2f C. f D. 1.5f
View Answer
A. 3f ✅ Exp: From lens equation, m = v/u = 2 → u = 3f.
Q77. Focal power of the eye decreases with:
A. Accommodation
B. Age
C. Convergence
D. Pupil dilation
View Answer
B. Age ✅ Exp: Presbyopia reduces accommodation amplitude.
Q78. A plus lens shifts the image focus:
A. Backward B. Forward C. No change D. Diverging
View Answer
A. Backward ✅ Exp: Converging lens brings rays forward focus.
Q79. A minus lens shifts focus:
A. Backward B. Forward C. Central D. No effect
View Answer
A. Backward ✅ Exp: Diverging lens pushes focus behind lens.
Q80. In a combined lens system, the equivalent focal length depends on:
A. Individual powers and separation B. Aperture only C. Glass type only D. Thickness alone
View Answer
A. Individual powers and separation ✅ Exp: defines total system power.
