Q11.The driver of 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 after it gets reflected from the wall. Find the speed of the bus if speed of the sound is 330 ms–1 : (1) 91 kmh−1 (2) 81 kmh−1 (3) 61 kmh−1 (4) 71 kmh−1
What This Question Tests
This problem involves a two-step application of the Doppler effect: first for sound reaching a stationary wall, and then for the reflected sound reaching the moving source (driver).
Concepts Tested
Formulas Used
f' = f * (v_sound / (v_sound - v_source))
f'' = f' * ((v_sound + v_observer) / v_sound)
📚 NCERT Sections This Tests
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📋 Question Details
- Chapter
- Waves & Sound
- Topic
- Doppler Effect (Reflection)
- Year
- 2020
- Shift
- 04 Sep Shift 2
- Q Number
- Q11
- Type
- MCQ
- NCERT Ref
- Class 11 Physics Ch 15: Waves
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