NEET Ray Optics and Optical Instruments PYQs & Practice Questions

10 free NEET Physics questions on Ray Optics and Optical Instruments, starting with previous year questions (2016–2026). Tap “Show answer” to check each one. No login needed.

Topics: Microscope · Lens Combinations · Refraction at Spherical Surfaces · Lens Formula and Magnification · Prism and Dispersion · Mirror Formula · Optical Instruments – Microscope · Refraction – Snell's Law and Total Internal Reflection · Lensmaker's Equation and Power of Lenses · Dispersion and Speed of Light in a Medium · Critical Angle and Wavelength Dependence · Refractive Index of Right-Angled Prism from Ray Geometry

1. Q1NEET 2026Apparent Depth in Multiple Media

   Consider three media P, Q and R with refractive indices 1, 1.25, and 1.5, respectively. The medium Q, having a thickness of 5 cm, is placed between extended media P and R as shown. An object O is placed at the center of medium Q. If viewed from medium P near the normal direction, the apparent depth of O is h1. For similar observation from medium R, the apparent depth is h2. The value of |h1 - h2|, in cm, is:

   • A. 1
   • B. 2
   • C. 3
   • D. 0
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   Answer: —

   O is at the center of the 5cm thick medium Q, so it is 2.5cm from each interface. Viewed from P: apparent depth h1 = real depth x (n_P/n_Q) = 2.5 x (1/1.25) = 2cm. Viewed from R: apparent depth h2 = real depth x (n_R/n_Q) = 2.5 x (1.5/1.25) = 3cm. |h1 - h2| = |2 - 3| = 1cm.

2. Q2NEET 2026Combination of Lenses

   A lens combination consists of two lenses, L₁ and L₂, of focal lengths +10 cm and −10 cm respectively, separated by 3 cm. An object O is placed 30 cm to the left of L₁ on the common principal axis. The position of the final image formed is:

   • A. 60 cm to the left of the concave lens
   • B. 30 cm to the right of the concave lens
   • C. 60 cm to the right of the concave lens
   • D. 20 cm to the left of the concave lens
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   Answer: —

   For L₁ (f=+10cm, u=-30cm): 1/v = 1/f + 1/u = 1/10 - 1/30 = 1/15, so v = 15 cm (image forms 15 cm to the right of L₁, i.e., 15-3=12 cm beyond L₂). This serves as a virtual object for L₂ at u₂=+12 cm. For L₂ (f=-10cm): 1/v₂ = 1/f₂ + 1/u₂ = -1/10 + 1/12 = -1/60, so v₂ = -60 cm. The negative sign means the final image forms 60 cm to the left of the concave lens L₂.

3. Q3NEET 2026Thin lens / concave lens refraction

   In a concave lens, a ray of light emanating from the object parallel to the principal axis of the lens, after refraction:

   • A. passes through the second principal focus
   • B. appears to diverge from the first principal focus
   • C. passes through 2F, which is the radius of curvature of the lens
   • D. emerges parallel to the principal axis
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   Answer: A — passes through the second principal focus

   A ray parallel to the principal axis, after refraction through a diverging (concave) lens, appears to diverge from the first (virtual) focus.

4. Q4NEET 2025Microscope

   A microscope has an objective of focal length 2 cm, eyepiece of focal length 4 cm and the tube length of 40 cm. If the distance of distinct vision of eye is 25 cm, the magnification in the microscope is -

   • A. 100
   • B. 125
   • C. 150
   • D. 250
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   Answer: A — 100

   M = L·D/(f0·fe) = (40×25)/(2×4) = 1000/8 = 125.

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5. Q5NEET 2025Lens Combinations

   In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power (p) and magnification (m) for each lens will be, respectively -

   • A. 4p and 4m
   • B. p⁴ and 4m
   • C. 4p and m⁴
   • D. p⁴ and m⁴
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   Answer: B — p⁴ and 4m

   For lenses in contact, net power Pnet = P1+P2+P3+P4 = 4P. Total magnification is the product of individual magnifications: mtotal = m×m×m×m = m⁴.

6. Q6NEET 2024Refractive Index of Right-Angled Prism from Ray Geometry

   A light ray enters through a right angled prism at point P with the angle of incidence 30° as shown in figure. It travels through the prism parallel to its base BC and emerges along the face AC. The refractive index of the prism is: [Figure: right-angled prism ABC with right angle at A, ray entering at P on AB with 30° incidence, traveling parallel to BC, emerging at AC]

   • A. √3/4
   • B. √3/2
   • C. √5/4
   • D. √5/2
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   Answer: C — √5/4

   For AB surface: sin30° = μsin(90°-C), so 1/2 = μcosC ...(i). For AC surface (critical angle, grazing emergence): μsinC = 1, so μ = 1/sinC ...(ii). Substituting (ii) into (i): 1/2 = cosC/sinC, so tanC = 2, giving sinC = 2/√5. From (ii): μ = 1/(2/√5) = √5/2.

7. Q7NEET 2024Astronomical Telescope - Magnifying Power

   A small telescope has an objective of focal length 140 cm and an eye piece of focal length 5.0 cm. The magnifying power of telescope for viewing a distant object is:

   • A. 17
   • B. 32
   • C. 34
   • D. 28
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   Answer: C — 34

   Magnifying power m = fo/fe = 140/5 = 28.

8. Q8NEET 2023Critical Angle Calculation

   Light travels a distance x in time t1 in air and 10x in time t2 in another denser medium. What is the critical angle for this medium?

   • A. sin^-1(10t2/t1)
   • B. sin^-1(t1/10t2)
   • C. sin^-1(10t1/t2)
   • D. sin^-1(t2/t1)
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   Answer: B — sin^-1(t1/10t2)

   v1 = x/t1 (speed in air/rarer medium), v2 = 10x/t2 (speed in denser medium). Refractive index μ = v1/v2 = (x/t1)/(10x/t2) = t2/(10t1). Critical angle: sin(ic) = 1/μ = 10t1/t2, so ic = sin^-1(10t1/t2).

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9. Q9NEET 2023Equivalent Focal Length - Convex and Concave Lens Combination

   Two thin lenses are of same focal lengths (f), but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be:

   • A. f/4
   • B. f/2
   • C. Infinite
   • D. Zero
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   Answer: B — f/2

   For lenses in contact, 1/F = 1/f1+1/f2 = 1/f + 1/(-f) = 0. So F = 1/0 = infinite, meaning the combination has no net converging or diverging power.

10. Q10NEET 2023Equivalent Focal Length - Liquid Lens Combination

    In the figure shown here, what is the equivalent focal length of the combination of lenses (Assume that all layers are thin)? [Figure shows a biconvex glass lens (n1=1.5) with liquid (n2=1.6) filled on both curved sides, R1=R2=20cm]

    • A. -40 cm
    • B. -100 cm
    • C. -50 cm
    • D. 40 cm
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    Answer: A — -40 cm

    The system consists of 3 lenses: two liquid plano-concave lenses (f1=f3=-100/3 cm each, using R/(μ-1) with μ=1.6) and the glass biconvex lens (f2=20cm, using R/(2(μ-1)) with μ=1.5). Combined: 1/F = 1/(-100/3) + 1/20 + 1/(-100/3) = -3/100+5/100-3/100 = -1/100, giving F = -100cm.