JEE Main 2023 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 6 April 2023, Shift 1, Physics Q51

Question 51 of 90 in this shift, Physics question 21 of 30, Section B.

A 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 of his car's horn upon reflection from the wall. The frequency of horn is ____________ Hz. (Given: Speed of sound : 330 m/s)

Official answer

420

NTA final key.

Chapter: Waves
Topic: Doppler Effect
Idea tested: Moving Reflector Echo

Same idea in other shifts

Asked 3× in all

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

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.