NEET PhysicsUpdated 19 Oct 2026

Ray Optics and Optical Instruments: NEET PYQs and weightage

Ray Optics and Optical Instruments carries 5.1 of 100 Physics marks in NEET by past-paper share: 39 of the 758 tagged NEET Physics PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 5 of 30 Physics chapters.

Take the 25-question Ray Optics and Optical Instruments test Formula sheet ↓All NEET Physics chapters

5.1/100 Weight in Physics

Exam importance (4/5, by past-paper share)

39 NEET PYQs

447 Practice questions

377 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Physics PYQs in the bank (39 of 758), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.

Ray Optics and Optical Instruments: formula sheet for NEET

14 formulas, each with when to use it. Copy it onto one page of your notebook: that page is this chapter's handbook.

Mirror equation
$\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$
$f = \frac{R}{2}$
$m = \frac{h ^{'}}{h} = - \frac{v}{u}$
Use it when: Any concave or convex mirror question asks for image position, size or nature.
Thin lens formula
$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$
$m = \frac{h ^{'}}{h} = \frac{v}{u}$
Use it when: An object is placed before a convex or concave lens ( $m > 0$ means erect and virtual, $m < 0$ means inverted and real).
Lens maker's formula
$\frac{1}{f} = (\frac{n _{2} - n _{1}}{n _{1}}) (\frac{1}{R _{1}} - \frac{1}{R _{2}})$
Use it when: Radii and refractive index are given, or a lens is dipped in a liquid ( $n_{1}$ = surrounding medium, $n_{2}$ = lens).
Power and lenses in contact
$P = \frac{1}{f}$
$P = P_{1} + P_{2} + P_{3} + \dots$
$\frac{1}{f} = \frac{1}{f _{1}} + \frac{1}{f _{2}} + \dots$
Use it when: Lenses touch each other or a prescription is in dioptre ( $f$ in metres; convex is $+$ , concave is $-$ ).
Combined magnification
$m = m_{1} \times m_{2} \times m_{3} \dots$
Use it when: An image from one lens becomes the object for the next.
Snell's law
$n_{1} sin i = n_{2} sin r$
$n_{21} = \frac{sin i}{sin r} = \frac{n _{2}}{n _{1}}$
Use it when: A ray crosses a flat boundary between two media.
Critical angle
$sin i_{c} = \frac{n _{rarer}}{n _{denser}} (= \frac{1}{n} for a medium in air)$
Use it when: Light goes from denser to rarer and you must decide if TIR happens (TIR needs $i > i_{c}$ ).
Apparent depth
$apparent depth = \frac{real depth}{n}$
Use it when: You look at the bottom of a tank or a slab almost along the normal.
Refraction at one spherical surface
$\frac{n _{2}}{v} - \frac{n _{1}}{u} = \frac{n _{2} - n _{1}}{R}$
Use it when: There is a single curved glass or water surface, not a full thin lens.
Prism geometry
$r_{1} + r_{2} = A$
$δ = i + e - A$
Use it when: You trace a ray through a prism at any angle of incidence.
Minimum deviation
$n = \frac{sin ( \frac{A + D _{m}}{2} )}{sin ( \frac{A}{2} )}$
$i = e$
$r_{1} = r_{2} = \frac{A}{2}$
Use it when: The question says "minimum deviation" (the ray inside runs parallel to the base).
Thin prism
$D_{m} = (n - 1) A$
Use it when: The prism angle $A$ is small (a few degrees).
Simple microscope
$m = 1 + \frac{D}{f} (image at the near point)$
$m = \frac{D}{f} (image at infinity)$
$D = 25 cm$
Use it when: One convex lens is used as a magnifier.
Compound microscope and telescope
$m = \frac{L}{f _{o}} \cdot \frac{D}{f _{e}} (microscope, image at infinity)$
$m = \frac{f _{o}}{f _{e}} (telescope)$
$tube length = f_{o} + f_{e}$
Use it when: A two-lens instrument is in normal adjustment ( $L$ = gap between the objective's second focus and the eyepiece's first focus).

Trap

Students drop the Cartesian sign convention. Every distance is measured from the pole or optical centre, and anything against the incident light is negative. That makes u negative for a real object and f negative for a concave mirror. Also, the mirror equation has "+" where the lens formula has "−".

How does NEET ask Ray Optics and Optical Instruments?

8 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.

Q1PhysicsNEET UG PYQRefraction of Light

Try right here · No sign-in

An air bubble in a glass slab with refractive index 1.5 (near normal incidence) is 5 cm deep when viewed from one face and 3 cm deep when viewed from the opposite face. The thickness (in cm) of the slab is

Answer key (B) & worked solution

Correct answer: Option B

H_{a pp} = \frac{H _{R}}{μ _{g}} \Rightarrow H_{R} = μ_{g} H_{a pp}

So,

H_{R 1} = μ_{g} H_{a pp 1}

and

H_{R 2} = μ_{g} H_{a pp 2}

So, thickness

= H_{R 1} + H_{R 2}

= μ_{g} [H_{a pp 1} + H_{a pp 2}] = \frac{3}{2} [5 + 3] = \frac{3}{2} \times 8 = 12 c m

Q2PhysicsNEET UG PYQRefraction of Light

Pick the wrong answer in the context with rainbow:

AThe order of colours is reversed in the secondary rainbow.

BAn observer can see a rainbow when his front is towards the sun.

CRainbow is a combined effect of dispersion, refraction and reflection of sunlight.

DWhen the light rays undergo two internal reflections in a water drop, a secondary rainbow is formed.

Answer key (B) & worked solution

Correct answer: Option B

Rainbow can't be observed when observer faces towards sun.

Q3PhysicsNEET UG PYQOptical Instruments

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

A150

B250

C100

D125

Answer key (D) & worked solution

Correct answer: Option D

It is a compound microscope

M_{objective} \approx \frac{L}{f _{0}} \approx \frac{40 c m}{2 c m} \approx 20 c m

Case 1: For relaxed eye (V = 0)

M P_{eyepiece} = \frac{D}{f _{e}} = \frac{25}{4} = 6.25

M_{compound} = 20 \times 6.25 = 125

(For relaxed eye

V = \infty

) Case 2: For

L D D V

M P_{eyepiece} = 1 + \frac{D}{f _{e}} = 7.25

M_{compound} = 20 \times 7.25 = 145

Note: They have NOT asked for maximum magnification explicitly.

Q4PhysicsNEET UG PYQRefraction at Spherical Surfaces and by Lenses

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 -

4 p

and

m^{4}

p^{4}

and

m^{4}

4 p

and

4 m

p^{4}

and

4 m

Answer key (A) & worked solution

Correct answer: Option A

Power is additive when lenses are in contact So each lens has power P, then 4 lenses

P_{total} = P + P + P + P = 4 P

Magnification

m_{total} = m \times m \times m \times m

(series)

= m^{4}

Q5PhysicsNEET UG PYQRefraction Through a Prism

The angle of incidence for a ray of light at a refracting surface of a prism is 45

^{o}

. The angle of prism is 60

^{o}

. If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are

A45

^{o}

\frac{1}{2}

B30

^{o}

2

C45

^{o}

2

D30

^{o}

\frac{1}{2}

Answer key (B) & worked solution

Correct answer: Option B

i = 45∘; A = 60∘; δ

_{m}

= 2i − A = 30

^{o}

μ = \frac{sin ( A + δ _{m} )}{sin \frac{A}{2}} = \frac{sin 4 5 ^{\circ}}{sin 3 0 ^{\circ}} = \frac{1}{2} . \frac{2}{1} = 2

Q6PhysicsNEET UG PYQReflection of Light by Spherical Mirrors

Match the corresponding entries of column-1 with column-2 (Where m is the magnification produced by the mirror) Column - 1Column – 2(A)m = -2(a)Convex mirror(B)m =

- \frac{1}{2}

(b)Concave mirror(C)m = + 2(c)Real image(D)m =

+ \frac{1}{2}

(d)Virtual image

AA → b and c, B → b and c, C → b and d, D → a and d

BA → a and c, B → a and d, C → a and b, D → c and d

CA → a and d, B → b and c, C → b and d, D → b and c

DA → c and d, B → b and d, C → b and c, D → a and d

Answer key (A) & worked solution

Correct answer: Option A

m = + ve ⇒ virtual image m = - ve ⇒ Real image |m| > 1⇒ magnified image |m| < 1⇒ diminished imagem is +ve for convex mirror and magnitude is less than one.

m is -ve & +ve for concave mirror

Q7PhysicsNEET UG PYQRefraction Through a Prism

A thin prism having refracting angle 10° is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be

A8°

B10°

C4°

D6°

Answer key (D) & worked solution

Correct answer: Option D

condition for dispersion without deviation:-

(μ - 1) A = (μ^{'} - 1) A^{'}

(1.42 - 1) \times 1 0^{\circ} = (1.7 - 1) A^{'}

4.2 = 0.7 A^{'}

A^{'} = 6^{\circ}

Q8PhysicsNEET UG PYQRefraction of Light

Light travels a distance

x

in time

t_{1}

in air and

10 x

in time

t_{2}

in another denser medium. What is the critical angle for this medium?

sin^{- 1} (\frac{10 t _{2}}{t _{1}})

sin^{- 1} (\frac{t _{1}}{10 t _{2}})

sin^{- 1} (\frac{10 t _{1}}{t _{2}})

sin^{- 1} (\frac{t _{2}}{t _{1}})

Answer key (C) & worked solution

Correct answer: Option C

Speed of light is air

V_{1} = \frac{x}{t _{1}}

Speed of light is a medium

V_{2} = \frac{10 x}{t _{2}}

sin θ_{c} = \frac{V _{2}}{V _{1}} = \frac{10 x}{t _{2}} \frac{t _{1}}{x}

θ_{c} = sin^{- 1} (\frac{10 t _{1}}{t _{2}})

Which topics in Ray Optics and Optical Instruments carry the most questions?

All 6 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
Refraction at Spherical Surfaces and by Lenses	13	134
Refraction Through a Prism	9	66
Refraction of Light	7	104
Optical Instruments	7	72
Reflection of Light by Spherical Mirrors	3	70
Miscellaneous Examples	0	1

Why does Ray Optics and Optical Instruments show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Ray Optics and Optical Instruments, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.

How ViJEEta scores you

What happens when you test Ray Optics and Optical Instruments?

Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.

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Chapters either side of Ray Optics and Optical Instruments by weight

Dual Nature of Radiation and Matter Weight 5.3/100 System of Particles and Rotational Motion Weight 5.3/100 Moving Charges and Magnetism Weight 4.6/100 Electrostatic Potential and Capacitance Weight 4.2/100

Ray Optics and Optical Instruments: NEET PYQs and weightage

Ray Optics and Optical Instruments: formula sheet for NEET

Mirror equation

Thin lens formula

Lens maker's formula

Power and lenses in contact

Combined magnification

Snell's law

Critical angle

Apparent depth

Refraction at one spherical surface

Prism geometry

Minimum deviation

Thin prism

Simple microscope

Compound microscope and telescope

How does NEET ask Ray Optics and Optical Instruments?

Which topics in Ray Optics and Optical Instruments carry the most questions?

Why does Ray Optics and Optical Instruments show "–" until you answer 3 questions?

What happens when you test Ray Optics and Optical Instruments?

Chapters either side of Ray Optics and Optical Instruments by weight