JEE Main · Physics · Wave Optics

Young's Double Slit: JEE Main previous year questions

Name: Young's Double Slit: JEE Main previous year questions
Creator: Lumi

56 questions in the 108 JEE Main shifts Lumi analysed, in 8 of 8 years. Pattern: Asked most years. 20 came in 2024–26. Here is how it is asked and which ideas come back.

Questions: 56; in 54 of 108 shifts
Years asked: 8/8; last asked 2026
Chance in a shift: 47%; calibrated model, how we compute it
Weighted estimate: 0.5; model; history: 0.5 a shift on average, typically 0.3–0.7

Key findings

01
Asked in 8 of 8 years with analysed shifts and in 54 of 108 shifts: 56 questions, #46 of 196 topics. It came in every year with analysed shifts.
02
31% of its questions since 2020 tested an idea no earlier year had asked; 29 repeated an idea from the year before.
03
The most repeated idea is YDSE Fringe Width, asked 14 times in 14 shifts (2020, 2021, 2022, 2023, 2024), most often as “distance between fringes in ydse”.
04
JEE Main has asked 16 of the 56 ideas in this topic; 35 have never been asked, directly or inside another question.
05
Mostly asked as single correct (57%); 41% need a numerical answer, 57% are easy and 0% hard.
06
The skill tested most is calculation (82%), then multi-step (7%).

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: 1 in 1 shift · 2020: 7 in 12 shifts · 2021: 10 in 24 shifts · 2022: 14 in 24 shifts · 2023: 4 in 12 shifts · 2024: 9 in 18 shifts · 2025: 5 in 8 shifts · 2026: 6 in 9 shifts.

Up to 2023: 0.5; a shift, of 25
Since 2024: 0.6; 0.1
Usual gap: 1.3 yrs; between years asking it
Shifts with it: 54/108; 50% of analysed shifts

Recent framings

numerical: intensity ratio at fractional path differences
numerical: path difference from intensity fraction
numerical: fringe width in different medium

Revise first

Resultant Intensity Formula · asked 2021, 2022, 2023, 2024, 2025
Intensity at Fractional Path Differences · asked 2020, 2024, 2026
Intensity Ratio from Slit Widths · asked 2021, 2022, 2024, 2025

How it is asked

Difficulty, format and skill

Across all 56 questions on Young's Double Slit since 2017.

Difficulty

QUESTIONS

3224

Easy32 · 57%
Medium24 · 43%
Hard0 · 0%

Format

Single correct · 32 Q57%
Numerical value · 23 Q41%
Diagram based · 1 Q2%

Skill tested

Calculation · 46 Q82%
Multi-step · 4 Q7%
Application · 3 Q5%
Conceptual · 3 Q5%

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.

’17’20’21’22’23’24’25’26

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

Coverage of the topic

JEE Main has asked 16 of the 56 ideas in this topic. 35 have never been asked yet.

1635

Asked directly16 · 29%
Touched inside another question5 · 9%
Never asked35 · 63%

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

Idea, year, question

Every idea JEE Main tested in this topic, with its eight years. Open one to read the questions.

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

OpenRepeated14 · 25%25%5/8273
- 5 Apr ’24 S1 · Q58
  In Young's double slit experiment, carried out with light of wavelength 5000 Å, the distance between the slits is 0.3 mm and the screen is…
  easyNumerical valueAsked the year before
- 8 Apr ’23 S2 · Q46
  The width of fringe is 2 mm on the screen in a double slits experiment for the light of wavelength of 400 nm. The width of the fringe for…
  easySingle correctAsked the year before
- 28 Jul ’22 S1 · Q53
  In a Young's double slit experiment, a laser light of 560 nm produces an interference pattern with consecutive bright fringes' separation…
  easyNumerical valueAsked the year before
- 29 Jun ’22 S1 · Q49
  Read the question
  easySingle correctAsked the year before
- 29 Jun ’22 S2 · Q59
  Read the question
  mediumNumerical valueAsked the year before
- 3 Aug ’21 S2 · Q27
  Read the question
  easyNumerical valueAsked the year before
- 26 Aug ’21 S1 · Q27
  Read the question
  mediumNumerical valueAsked the year before
- 31 Aug ’21 S2 · Q24
  Read the question
  easyNumerical valueAsked the year before
- 24 Feb ’21 S2 · Q14
  Read the question
  easySingle correctAsked the year before
- 26 Feb ’21 S1 · Q17
  Read the question
  easySingle correctAsked the year before
- 25 Jul ’21 S1 · Q8
  Read the question
  mediumSingle correctAsked the year before
- 18 Mar ’21 S1 · Q7
  Read the question
  easySingle correctAsked the year before
- 9 Jan ’20 S2 · Q24
  Read the question
  easyNumerical valueNew idea
- 2 Sep ’20 S2 · Q16
  Read the question
  easySingle correctNew idea
OpenRepeated13 · 23%23%5/85232
OpenRepeated6 · 11%11%3/823
OpenRepeated6 · 11%11%4/822
OpenRepeated3 · 5%5%3/8
OpenRepeated2 · 4%4%2/8
OpenRepeated2 · 4%4%2/8
OpenRepeated2 · 4%4%2/8
Open1 · 2%2%1/8
Open1 · 2%2%1/8
Open1 · 2%2%1/8
Open1 · 2%2%1/8
Open1 · 2%2%1/8
Open1 · 2%2%1/8
Open1 · 2%2%1/8
Open1 · 2%2%1/8

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

16 different ideas were tested; 8 came more than once.

YDSE Fringe Width14×
distance between fringes in ydse
Numerical value · 14 shifts · 7 numerical
Resultant Intensity Formula13×
max minus min intensity of two beams
Single correct · 13 shifts · 6 numerical
Intensity at Fractional Path Differences6×
path difference from intensity fraction
Numerical value · 6 shifts · 3 numerical
Intensity Ratio from Slit Widths6×
max to min intensity ratio
Single correct · 5 shifts
Fringe Shift by Thin Slab3×
slab thickness from fringe shift
Numerical value · 3 shifts · 2 numerical
Effect of Medium on Fringes2×
fringe width in different medium
Single correct · 2 shifts
Coinciding Maxima of Two Wavelengths2×
order of overlapping fringes of two wavelengths
Numerical value · 2 shifts · 2 numerical
Angular Fringe Width2×
fringe angular width in a medium
Numerical value · 2 shifts · 1 numerical
Intensity Exactly Opposite a Slit1×
intensity opposite a slit in double slit
Single correct · 1 shift
White Light Interference1×
conceptual
Single correct · 1 shift
Exact Path Difference without Approximation1×
slit separation for dark fringe at point
Numerical value · 1 shift · 1 numerical
Position of nth Maximum and Minimum1×
wavelength from first dark fringe position
Numerical value · 1 shift · 1 numerical
Fringe Visibility and Contrast1×
fringe visibility from source intensity ratio
Single correct · 1 shift
Optical Path Length Calculation1×
phase difference after paths in different media
Single correct · 1 shift
Position of nth Fringe1×
path difference at fringe position
Single correct · 1 shift
Coincidence of Polychromatic Fringes1×
coincidence of fringes of two wavelengths
Single correct · 1 shift

Idea	Times	Shifts	Format	Numerical
YDSE Fringe Widthdistance between fringes in ydse	14	14	Numerical valueCalculation	7
Resultant Intensity Formulamax minus min intensity of two beams	13	13	Single correctCalculation	6
Intensity at Fractional Path Differencespath difference from intensity fraction	6	6	Numerical valueCalculation	3
Intensity Ratio from Slit Widthsmax to min intensity ratio	6	5	Single correctCalculation	–
Fringe Shift by Thin Slabslab thickness from fringe shift	3	3	Numerical valueCalculation	2
Effect of Medium on Fringesfringe width in different medium	2	2	Single correctApplication	–
Coinciding Maxima of Two Wavelengthsorder of overlapping fringes of two wavelengths	2	2	Numerical valueCalculation	2
Angular Fringe Widthfringe angular width in a medium	2	2	Numerical valueCalculation	1
Intensity Exactly Opposite a Slitintensity opposite a slit in double slit	1	1	Single correctCalculation	–
White Light Interferenceconceptual	1	1	Single correctConceptual	–
Exact Path Difference without Approximationslit separation for dark fringe at point	1	1	Numerical valueMulti-step	1
Position of nth Maximum and Minimumwavelength from first dark fringe position	1	1	Numerical valueCalculation	1
Fringe Visibility and Contrastfringe visibility from source intensity ratio	1	1	Single correctCalculation	–
Optical Path Length Calculationphase difference after paths in different media	1	1	Single correctApplication	–
Position of nth Fringepath difference at fringe position	1	1	Single correctCalculation	–
Coincidence of Polychromatic Fringescoincidence of fringes of two wavelengths	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

Young's Double Slit questions, year by year

The newest 40 show their opening words as they appeared in the official paper; older ones name the idea they tested. Open one for its options and the official answer.

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.

Key findings

Questions a shift, year by year

Difficulty, format and skill

Difficulty

Format

Skill tested

New idea, or one asked before?

Coverage of the topic

Idea, year, question

Every idea inside this topic

Young's Double Slit questions, year by year

JEE Main 20266 questions in 6 shifts

JEE Main 20255 questions in 4 shifts

JEE Main 20249 questions in 9 shifts

JEE Main 20234 questions in 4 shifts

JEE Main 202214 questions in 13 shifts

JEE Main 202110 questions in 10 shifts

JEE Main 20207 questions in 7 shifts

JEE Main 20171 question in 1 shift

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