JEE Main · Physics · Wave Optics
Single Slit Diffraction: JEE Main previous year questions
17 questions in the 108 JEE Main shifts Lumi analysed, in 7 of 8 years. Pattern: Asked most years. 11 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 17
- in 17 of 108 shifts
- Years asked
- 7/8
- last asked 2026
- Weighted estimate
- 0.2
- model; history: 0.2 a shift on average, typically 0.0–0.3
Key findings
- 01
Asked in 7 of 8 years with analysed shifts and in 17 of 108 shifts: 17 questions, #152 of 196 topics.
- 02
53% of its questions since 2020 tested an idea no earlier year had asked; 5 repeated an idea from the year before.
- 03
The most repeated idea is Single Slit Minima Condition, asked 5 times in 5 shifts (2023, 2024, 2025, 2026), most often as “separation between diffraction minima”.
- 04
JEE Main has asked 9 of the 57 ideas in this topic; 46 have never been asked, directly or inside another question.
- 05
Mostly asked as numerical value (53%); 53% need a numerical answer, 47% are easy and 0% hard. It went up from 0.1 to 0.3 questions a shift since 2024.
- 06
The skill tested most is calculation (88%), then multi-step (6%).
Questions a shift, year by year
Out of the 25 Physics questions in a shift. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift.
Raw count: 2017: 0 in 1 shift · 2020: 2 in 12 shifts · 2021: 1 in 24 shifts · 2022: 2 in 24 shifts · 2023: 1 in 12 shifts · 2024: 6 in 18 shifts · 2025: 2 in 8 shifts · 2026: 3 in 9 shifts.
- Up to 2023
- 0.1
- a shift, of 25
- Since 2024
- 0.3
- 0.2
- Usual gap
- 1.0 yrs
- between years asking it
- Shifts with it
- 17/108
- 16% of analysed shifts
How it is asked
Difficulty, format and skill
Across all 17 questions on Single Slit Diffraction since 2017.
Difficulty
QUESTIONS- Easy8 · 47%
- Medium9 · 53%
- Hard0 · 0%
Format
SHARE- Numerical value · 9 Q53%
- Single correct · 8 Q47%
Skill tested
SHARE- Calculation · 15 Q88%
- Multi-step · 1 Q6%
- Conceptual · 1 Q6%
Repeats
New idea, or one asked before?
Each column is a year. Blue questions tested an idea no earlier year had asked; navy ones went back to an idea from an earlier year. 2017 is the first year, so everything in it counts as new. Heights are question counts, and Lumi analysed 1 to 24 shifts a year, so compare the split inside a column rather than heights across years.
- Idea asked for the first time
- Idea asked in an earlier year
Coverage of the topic
JEE Main has asked 9 of the 57 ideas in this topic. 46 have never been asked yet.
- Asked directly9 · 16%
- Touched inside another question2 · 4%
- Never asked46 · 81%
Ideas come from Lumi’s JEE syllabus map. A never-asked idea is not a safe skip: across all of JEE Main, 22% of questions since 2024 tested an idea no earlier year had asked.
Drill down
Chapter, idea, question
Every idea JEE Main tested in this topic, with its eight years. Open one to read the questions.
9 ideas inside
Squares are the 8 years with analysed shifts, 2017 to 2026. A number is the questions that year when there is more than one; the shade is scaled to one shift, so a year with more analysed shifts (1 to 24 a year) does not look darker. Share is of the level above.
Ideas
Every idea inside this topic
9 different ideas were tested; 4 came more than once.
separation between diffraction minima
Numerical value · 5 shifts · 3 numericalangular width of central maximum
Single correct · 3 shifts · 1 numericaltelescope aperture from resolution
Numerical value · 2 shifts · 1 numericalslit width from fringes in central maximum
Numerical value · 2 shifts · 2 numericallinear width of central maximum
Single correct · 1 shiftwidth of secondary maximum
Single correct · 1 shiftseparation of first maxima for two wavelengths
Numerical value · 1 shift · 1 numericalcount of diffraction minima for slit
Numerical value · 1 shift · 1 numericalminimum resolvable separation for telescope
Single correct · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Single Slit Minima Conditionseparation between diffraction minima | 5 | 5 | Numerical valueCalculation | 3 | |
| Angular Width of Central Maxangular width of central maximum | 3 | 3 | Single correctCalculation | 1 | |
| Resolving Power of a Telescopetelescope aperture from resolution | 2 | 2 | Numerical valueCalculation | 1 | |
| Diffraction Envelope in YDSEslit width from fringes in central maximum | 2 | 2 | Numerical valueCalculation | 2 | |
| Linear Width of Central Maxlinear width of central maximum | 1 | 1 | Single correctCalculation | – | |
| Width of Secondary Maximawidth of secondary maximum | 1 | 1 | Single correctCalculation | – | |
| Secondary Maxima Conditionseparation of first maxima for two wavelengths | 1 | 1 | Numerical valueCalculation | 1 | |
| Maximum Observable Minimacount of diffraction minima for slit | 1 | 1 | Numerical valueCalculation | 1 | |
| Rayleigh Criterionminimum resolvable separation for telescope | 1 | 1 | Single correctCalculation | – |
Times and shifts count every analysed shift. Across JEE Main, 78% of questions since 2024 went back to an idea an earlier year had asked; the rest were new. All repeated ideas
Every question
Single Slit Diffraction questions, year by year
The opening words of each question as it appeared in the official paper, with the idea it tested. Open one for its options and the official answer.
JEE Main 20263 questions in 3 shifts
- 2 Apr, Shift 1Q46In single slit diffraction pattern, the wavelength of light used is nm and slit width is mm, the angular width of central…
Idea: Angular Width of Central Max
EasyNumerical value - 4 Apr, Shift 1Q33A slit of width is illuminated by light of wavelength . The linear separation between and …
Idea: Single Slit Minima Condition
Asked the year beforeEasySingle correct - 8 Apr, Shift 2Q47Some distant star is to be observed by some telescope of diameter of objective lens , at an angular resolution of …
Idea: Resolving Power of a Telescope
EasyNumerical value
JEE Main 20252 questions in 2 shifts
- 2 Apr, Shift 1Q50If the measured angular separation between the second minimum to the left of the central maximum and the third minimum to the right of the…
Idea: Single Slit Minima Condition
Asked the year beforeMediumNumerical value - 4 Apr, Shift 2Q46In a Young's double slit experiment, two slits are located 1.5 mm apart. The distance of screen from slits is 2 m and the wavelength of…
Idea: Diffraction Envelope in YDSE
Asked the year beforeMediumNumerical value
JEE Main 20246 questions in 6 shifts
- 5 Apr, Shift 2Q53In a single slit experiment, a parallel beam of green light of wavelength 550 nm passes through a slit of width 0.20 mm. The transmitted…
Idea: Single Slit Minima Condition
Asked the year beforeEasyNumerical value - 8 Apr, Shift 1Q59A parallel beam of monochromatic light of wavelength 600 nm passes through single slit of 0.4 mm width. Angular divergence corresponding…
Idea: Single Slit Minima Condition
Asked the year beforeEasyNumerical value - 8 Apr, Shift 2Q59Two slits are 1 mm apart and the screen is located 1 m away from the slits. A light of wavelength 500 nm is used. The width of each slit…
Idea: Diffraction Envelope in YDSE
New ideaMediumNumerical value - 1 Feb, Shift 1Q45A monochromatic light of wavelength 6000 is incident on the single slit of width 0.01 mm. If the diffraction pattern is…
Idea: Linear Width of Central Max
New ideaMediumSingle correct - 1 Feb, Shift 2Q45A microwave of wavelength 2.0 cm falls normally on a slit of width 4.0 cm. The angular spread of the central maxima of the diffraction…
Idea: Angular Width of Central Max
EasySingle correct - 30 Jan, Shift 1Q45The diffraction pattern of a light of wavelength 400 nm diffracting from a slit of width 0.2 mm is focused on the focal plane of a convex…
Idea: Width of Secondary Maxima
New ideaMediumSingle correct
JEE Main 20231 question in 1 shift
- 15 Apr, Shift 1Q46A single slit of width is illuminated by a monochromatic light of wavelength 600 nm. The value of '' for which first minimum…
Idea: Single Slit Minima Condition
New ideaEasySingle correct
JEE Main 20222 questions in 2 shifts
- 24 Jun, Shift 1Q55Sodium light of wavelengths 650 nm and 655 nm is used to study diffraction at a single slit of aperture 0.5 mm. The distance between the…
Idea: Secondary Maxima Condition
New ideaMediumNumerical value - 28 Jun, Shift 1Q43The aperture of the objective is 24.4 cm. The resolving power of this telescope, if a light of wavelength 2440 is used to…
Idea: Resolving Power of a Telescope
New ideaEasySingle correct
JEE Main 20211 question in 1 shift
- 25 Feb, Shift 2Q14Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter 0.1 µm. If the diameter of the pinhole is…
Idea: Angular Width of Central Max
New ideaMediumSingle correct
JEE Main 20202 questions in 2 shifts
- 9 Jan, Shift 1Q16The aperture diameter of a telescope is 5 m. The separation between the moon and the earth is km. With light of wavelength…
Idea: Rayleigh Criterion
New ideaMediumSingle correct - 4 Sep, Shift 2Q25Orange light of wavelength m illuminates a single slit of width m. The maximum possible number of…
Idea: Maximum Observable Minima
New ideaMediumNumerical value
Questions from the official JEE Main Paper 1 shifts published by NTA (CBSE for 2017). Questions NTA dropped are left out. Topic and idea tags, counts and notes are Lumi’s.