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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 26 August 2021, Shift 1, Physics Q30

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

A 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 detects a frequency of 1800 Hz of the sound coming from the source, then the original frequency of source considering speed of sound in air 340 m/s will be __________ Hz.

Official answer

2025

NTA final key.

Chapter
Waves
Topic
Doppler Effect
Idea tested
General Doppler Formula

Same idea in other shifts

Asked 2× in all
  1. 27 Aug 2021, Shift 1 · Q25Two 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…EasyNumerical 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.