JEE Main 2022 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 26 July 2022, Shift 1, Physics Q54

Question 54 of 90 in this shift, Physics question 24 of 30, Section B.

When 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 with the car, the frequency will be

\frac{x}{3}

Hz where

x =

__________.

Official answer

200

NTA final key.

Chapter: Waves
Topic: Doppler Effect
Idea tested: Moving Source Cases

Same idea in other shifts

Asked 3× in all

8 Apr 2023, Shift 1 · Q31The engine of a train moving with speed $10\ \mathrm{ms^{-1}}$ towards a platform sounds a whistle at frequency $400\ \mathrm{Hz}$ . The…EasySingle correct
11 Apr 2023, Shift 2 · Q31A car P travelling at $20\ \mathrm{ms^{-1}}$ sounds its horn at a frequency of $400\ \mathrm{Hz}$ . Another car Q is travelling behind the…MediumSingle correct

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.