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Saturday, 31 October

JEE Main 2023 · PhysicsMultiple choiceSingle correctEasyConceptual

JEE Main 8 April 2023, Shift 1, Physics Q31

Question 31 of 90 in this shift, Physics question 1 of 30, Section A.

The engine of a train moving with speed 10 ms−110\ \mathrm{ms^{-1}} towards a platform sounds a whistle at frequency 400 Hz400\ \mathrm{Hz}. The frequency heard by a passenger inside the train is: (neglect air speed. Speed of sound in air = 330 ms−1330\ \mathrm{ms^{-1}})
  1. (1)200 Hz200\ \mathrm{Hz}
  2. (2)388 Hz388\ \mathrm{Hz}
  3. (3)412 Hz412\ \mathrm{Hz}
  4. (4)400 Hz400\ \mathrm{Hz}Official answer

Official answer

Option 4

NTA final key.

Chapter
Waves
Topic
Doppler Effect
Idea tested
Moving Source Cases

Same idea in other shifts

Asked 3× in all
  1. 11 Apr 2023, Shift 2 · Q31A car P travelling at 20 ms−120\ \mathrm{ms^{-1}} sounds its horn at a frequency of 400 Hz400\ \mathrm{Hz}. Another car Q is travelling behind the…MediumSingle correct
  2. 26 Jul 2022, Shift 1 · Q54When 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…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.