JEE Main · Physics · Waves
Doppler Effect: JEE Main previous year questions
15 questions in the 108 JEE Main shifts Lumi analysed, in 5 of 8 years. Pattern: Gone quiet. 0 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 15
- in 15 of 108 shifts
- Years asked
- 5/8
- last asked 2023
- Since 2024
- Quiet
- 0 questions in 2024–26
- Weighted estimate
- –
- history: 0.2 a shift on average, typically 0.0–0.2
Key findings
- 01
Asked in 5 of 8 years with analysed shifts and in 15 of 108 shifts: 15 questions, #158 of 196 topics. The years that asked it were 1.5 apart on average. Last asked in 2023.
- 02
57% 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 Moving Reflector Echo, asked 3 times in 3 shifts (2020, 2022, 2023), most often as “frequency from echo shift off wall”.
- 04
JEE Main has asked 8 of the 57 ideas in this topic; 48 have never been asked, directly or inside another question.
- 05
Mostly asked as numerical value (60%); 60% need a numerical answer, 33% are easy and 0% hard. It went down from 0.3 to 0.0 questions a shift since 2024.
- 06
The skill tested most is calculation (87%), then conceptual (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: 1 in 12 shifts · 2021: 4 in 24 shifts · 2022: 6 in 24 shifts · 2023: 3 in 12 shifts · 2024: 0 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.
- Up to 2023
- 0.3
- a shift, of 25
- Since 2024
- 0.0
- -0.3
- Usual gap
- 1.5 yrs
- between years asking it
- Shifts with it
- 15/108
- 14% of analysed shifts
How it is asked
Difficulty, format and skill
Across all 15 questions on Doppler Effect since 2017.
Difficulty
QUESTIONS- Easy5 · 33%
- Medium10 · 67%
- Hard0 · 0%
Format
SHARE- Numerical value · 9 Q60%
- Single correct · 6 Q40%
Skill tested
SHARE- Calculation · 13 Q87%
- Conceptual · 1 Q7%
- Multi-step · 1 Q7%
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 8 of the 57 ideas in this topic. 48 have never been asked yet.
- Asked directly8 · 14%
- Touched inside another question1 · 2%
- Never asked48 · 84%
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.
7 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
8 different ideas were tested; 5 came more than once.
frequency from echo shift off wall
Numerical value · 3 shifts · 2 numericaldoppler with observer moving along with source
Single correct · 3 shifts · 1 numericalbeat frequency of direct and reflected sound
Numerical value · 2 shifts · 2 numericalvelocity from doppler shift of light
Numerical value · 2 shifts · 1 numericalsource frequency from observed frequency, moving source and observer
Numerical value · 2 shifts · 2 numericalapparent frequency with moving observer and wind
Numerical value · 1 shift · 1 numericalpercentage change in frequency for moving observer
Single correct · 1 shiftrelativistic doppler frequency
Single correct · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Moving Reflector Echofrequency from echo shift off wall | 3 | 3 | Numerical valueCalculation | 2 | |
| Moving Source Casesdoppler with observer moving along with source | 3 | 3 | Single correctCalculation | 1 | |
| Doppler Beat Frequency Calculationbeat frequency of direct and reflected sound | 2 | 2 | Numerical valueCalculation | 2 | |
| Light Doppler Approximationvelocity from doppler shift of light | 2 | 2 | Numerical valueCalculation | 1 | |
| General Doppler Formulasource frequency from observed frequency, moving source and observer | 2 | 2 | Numerical valueCalculation | 2 | |
| Effect of Wind Velocityapparent frequency with moving observer and wind | 1 | 1 | Numerical valueCalculation | 1 | |
| Moving Observer Casespercentage change in frequency for moving observer | 1 | 1 | Single correctCalculation | – | |
| Exact Relativistic Doppler Formularelativistic doppler frequency | 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
Doppler Effect 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 20233 questions in 3 shifts
- 6 Apr, Shift 1Q51A person driving car at a constant speed of 15 m/s is approaching a vertical wall. The person notices a change of 40 Hz in the frequency…
Idea: Moving Reflector Echo
Asked the year beforeMediumNumerical value - 8 Apr, Shift 1Q31The engine of a train moving with speed towards a platform sounds a whistle at frequency . The…
Idea: Moving Source Cases
Asked the year beforeEasySingle correct - 11 Apr, Shift 2Q31A car P travelling at sounds its horn at a frequency of . Another car Q is travelling behind the…
Idea: Moving Source Cases
Asked the year beforeMediumSingle correct
JEE Main 20226 questions in 6 shifts
- 25 Jul, Shift 1Q55An observer is riding on a bicycle and moving towards a hill at . He hears a sound from a source at some distance…
Idea: Doppler Beat Frequency Calculation
Asked the year beforeMediumNumerical value - 26 Jul, Shift 1Q54When a car is approaching the observer, the frequency of horn is 100 Hz. After passing the observer, it is 50 Hz. If the observer moves…
Idea: Moving Source Cases
New ideaMediumNumerical value - 28 Jul, Shift 1Q57The frequency of echo will be __________ Hz if the train blowing a whistle of frequency 320 Hz is moving with a velocity of 36 km/h…
Idea: Moving Reflector Echo
MediumNumerical value - 26 Jun, Shift 2Q46For a specific wavelength 670 nm of light coming from a galaxy moving with velocity , the observed wavelength is 670.7 nm. The value of…
Idea: Light Doppler Approximation
Asked the year beforeEasySingle correct - 27 Jun, Shift 1Q46An observer moves towards a stationary source of sound with a velocity equal to one-fifth of the velocity of sound. The percentage change…
Idea: Moving Observer Cases
New ideaEasySingle correct - 30 Jun, Shift 1Q52An employee of a factory moving away from his workplace by a car listens to the siren of the factory. He drives the car at the speed of 72…
Idea: Effect of Wind Velocity
New ideaMediumNumerical value
JEE Main 20214 questions in 4 shifts
- 26 Aug, Shift 1Q30A source and a detector move away from each other in absence of wind with a speed of 20 m/s with respect to the ground. If the detector…
Idea: General Doppler Formula
New ideaMediumNumerical value - 27 Aug, Shift 1Q25Two cars X and Y are approaching each other with velocities 36 km/h and 72 km/h respectively. The frequency of a whistle sound as emitted…
Idea: General Doppler Formula
New ideaEasyNumerical value - 24 Feb, Shift 2Q25Two cars are approaching each other at an equal speed of 7.2 km/hr. When they see each other, both blow horns having frequency of 676 Hz.…
Idea: Doppler Beat Frequency Calculation
New ideaMediumNumerical value - 18 Mar, Shift 2Q27A galaxy is moving away from the earth at a speed of 286 kms. The shift in the wavelength of a redline at 630 nm is…
Idea: Light Doppler Approximation
New ideaEasyNumerical value
JEE Main 20201 question in 1 shift
- 4 Sep, Shift 2Q10The driver of a bus approaching a big wall notices that the frequency of his bus's horn changes from 420 Hz to 490 Hz when he hears it…
Idea: Moving Reflector Echo
New ideaMediumSingle correct
JEE Main 20171 question in 1 shift
- 2 Apr (offline)Q13An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the…
Idea: Exact Relativistic Doppler Formula
MediumSingle correct
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.