NEET UG · Physics · Ray Optics and Optical Instruments

Snell's Law: NEET previous year questions

8 questions in ten years of NEET, in 7 of 10 papers. Pattern: Every year. Here is how it is asked and which ideas come back.

Asked in 10 years: 8; about 0.8 per paper
Years asked: 7/10; last asked 2026
Chance of a question next paper: 64%; historical rate, how we compute it
Weighted estimate: 0.8; model; history: 0.8 a paper on average, typically 0–1

Key findings

01
Asked in 7 of 10 papers, 8 questions in all: #100 of 204 topics by ten-year total. It comes back every 1.3 years on average.
02
63% of its questions since 2018 tested an idea never asked before; 1 repeated an idea from the year before.
03
The most repeated idea is Critical Angle and TIR, asked 3 times (2019, 2022, 2023), usually as “numerical”.
04
NEET has asked 5 of the 88 ideas in this topic; 78 have never been asked, directly or indirectly.
05
Mostly asked as numerical (63%); 13% easy, 13% hard.

Questions per year

Up to 2023: 0.8; per paper
Since 2024: 0.6; -0.2
Usual gap: 1.3 yrs; between papers asking it
Swing: ±0.6; questions, year to year

How it is asked

Difficulty, format and skill

Across all 8 questions on Snell's Law since 2017.

Difficulty

QUESTIONS

161

Easy1 · 13%
Medium6 · 75%
Hard1 · 13%

Format

Numerical · 5 Q63%
Figure-based · 2 Q25%
One-line MCQ · 1 Q13%

Skill tested

Multi-step · 4 Q50%
Application · 2 Q25%
Calculation · 1 Q13%
Concept · 1 Q13%

Repeats

New idea, or one asked before?

Each column is a paper. Blue questions tested an idea NEET had not asked before; navy ones went back to an idea from an earlier paper. 2017 is the first paper, so everything in it counts as new.

’17’18’19’20’21’22’23’24’25’26

Idea asked for the first time
Idea asked in an earlier paper

Coverage of the topic

NEET has asked 5 of the 88 ideas in this topic. 78 have never been asked yet.

Asked directly5 · 6%
Touched inside another question5 · 6%
Never asked78 · 89%

Ideas come from Lumi’s syllabus map of NCERT. A never-asked idea is not a safe skip: most new questions come from exactly these.

Drill down

Idea, year, question

Every idea NEET tested in this topic, with its ten papers. Open one to read the questions.

ideaAskedShareYears’17’18’19’20’21’22’23’24’25’26

Repeated3 · 38%38%3/10
- 2023 · Q8
  Light travels a distance $x$ in time $t_1$ in air and $10x$ in time $t_2$ in another denser medium. What is the critical angle for this…
  mediumNumericalAsked the year before
- 2022 · Q47
  Two transparent media A and B are separated by a plane boundary. The speed of light in those media are $1.5\times10^{8}$ m/s and…
  mediumNumerical
- 2019 · Q28
  In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be…
  easyOne-line MCQNew idea
Repeated2 · 25%25%2/10
1 · 13%13%1/10
1 · 13%13%1/10
1 · 13%13%1/10

Squares are the ten papers, 2017 to 2026; darker means more questions. Share is of the level above.

Ideas

Every idea inside this topic

5 different ideas were tested; 2 came more than once. Snell's Law Calculation is the foundation for 64 other ideas in the syllabus.

Critical Angle and TIR3×
numerical
Numerical · 6% next · foundation for 14
Snell's Law Calculation2×
numerical
Figure-based · 4% next · foundation for 64
Apparent Depth for Non-Air Observer1×
numerical
Numerical · 6% next
Grazing Emergence Condition1×
numerical
Figure-based · 6% next
Brewster's Angle and Snell's Law1×
numerical
Numerical · 4% next

Idea	Times	Format	Chance next	Foundation for
Critical Angle and TIRnumerical	3	NumericalCalculation	6%	14 ideas
Snell's Law Calculationnumerical	2	Figure-basedApplication	4%	64 ideas
Apparent Depth for Non-Air Observernumerical	1	NumericalMulti-step	6%	–
Grazing Emergence Conditionnumerical	1	Figure-basedMulti-step	6%	–
Brewster's Angle and Snell's Lawnumerical	1	NumericalApplication	4%	–

Chance next is the historical rate at which an idea with this record came back in the following paper. It is low for every idea, which is why learning the topic beats memorising past questions. All repeated ideas

Every question

Snell's Law questions, year by year

The opening words of each question as it appeared in the official paper, with the idea it tested.

NEET 20261 question

Q22
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…
Idea: Apparent Depth for Non-Air Observer
New ideaMediumNumerical · figure

NEET 20241 question

Q14
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…
Idea: Grazing Emergence Condition
New ideaHardFigure-based · figure

NEET 20231 question

Q8
Light travels a distance $x$ in time $t_1$ in air and $10x$ in time $t_2$ in another denser medium. What is the critical angle for this…
Idea: Critical Angle and TIR
Asked last yearMediumNumerical

NEET 20222 questions

Q22
A light ray falls on a glass surface of refractive index $\sqrt{3}$ , at an angle 60°. The angle between the refracted and reflected rays…
Idea: Brewster's Angle and Snell's Law
New ideaMediumNumerical
Q47
Two transparent media A and B are separated by a plane boundary. The speed of light in those media are $1.5\times10^{8}$ m/s and…
Idea: Critical Angle and TIR
MediumNumerical

NEET 20211 question

Q30
Find the value of the angle of emergence from the prism. Refractive index of the glass is $\sqrt{3}$ .
Idea: Snell's Law Calculation
MediumFigure-based · figure

NEET 20191 question

Q28
In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be…
Idea: Critical Angle and TIR
New ideaEasyOne-line MCQ

NEET 20181 question

Q19
The refractive index of the material of a prism is $\sqrt{2}$ and the angle of the prism is 30°. One of the two refracting surfaces of the…
Idea: Snell's Law Calculation
New ideaMediumNumerical

Questions from the official NEET UG papers published by NTA (CBSE before 2019). Topic and idea tags, counts and notes are Lumi’s.