JEE Main · Physics · Waves
Moving Reflector Echo
JEE Main asked Moving Reflector Echo 3 times in 3 of the 108 shifts Lumi analysed, in 2020, 2022 and 2023. It belongs to Doppler Effect, in Waves (Physics). The longest wait between two years asking it was 2 years.
Updated 2026-10-24
- Times asked
- 3
- in 3 shifts
- Years
- 3 of 8
- First asked
- 2020
- last in 2023
- Pattern
- Comes in cycles
- across the analysed shifts
Questions on this idea a shift, by year
2017–2026. Asked in 2020, 2022 and 2023. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift of 25 Physics questions.
Raw count: 2017: 0 in 1 shift · 2020: 1 in 12 shifts · 2021: 0 in 24 shifts · 2022: 1 in 24 shifts · 2023: 1 in 12 shifts · 2024: 0 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.
Shift by shift
Each square is one analysed shift, in date order. Open a filled one for that paper.
How JEE Main framed it
Numerical value is the usual form. Skill tested: calculation.
- Frequency from echo shift off wall
- Echo frequency for moving source
Difficulty
2 of the 3 questions had a numerical answer.
Every question
All 3 questions
From the official JEE Main shift papers, newest first. Open one for the full question, the options and the official answer.
- 6 Apr 2023, Shift 1 · Q51A 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…MediumNumerical value
- 28 Jul 2022, Shift 1 · Q57The 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…MediumNumerical value
- 4 Sep 2020, Shift 2 · Q10The 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…MediumSingle correct
Shifts: 4 Sep 2020, Shift 2, 28 Jul 2022, Shift 1, 6 Apr 2023, Shift 1.
Same topic
Other ideas in Doppler Effect
Doppler Effect has 8 ideas JEE Main has asked; 5 of them came up in more than one question.
- Moving Source Cases3× · 2023
- Doppler Beat Frequency Calculation2× · 2022
- Light Doppler Approximation2× · 2022
- General Doppler Formula2× · 2021
- Effect of Wind Velocityonce · 2022
- Moving Observer Casesonce · 2022
- Exact Relativistic Doppler Formulaonce · 2017