Echo

Tested in 3 real MPSC questions across 2 years (2017–2020). See it in context on the interactive Concept Graph →

Years it was asked

2020 2017

Real questions that test this

समुद्राची खोली काढण्यासाठी या तंत्राचा वापर करतात : To determine the depth of sea this technique is used :

a)(1) थर्मल डिटेक्टर / Thermal detector

b)(2) कुंडस् ट्युब / Kundt's tube

c)(3) ऑसिलेटर / Oscillator

d)(4) सोनार (SONAR) / SONAR&check; Correct

SONAR (Sound Navigation and Ranging) uses ultrasonic waves to measure distances and determine the depth of the sea by timing the echo return.

जेव्हा एखाद्या ध्वनी तरंगाचे संपीड़न दृढ भंतीवर आदळेल तेव्हा त्याचे प्रतिबिंबित रूप हे : When a compression of sound waves is incident on rigid wall, it is reflected as :

1)180 अंशानी (π) अवस्था संकुचीत होईल. / Compression with a phase change of π (by 180°)

2)अवस्था बदल होणार नाही. / Compression with no phase change&check; Correct

3)90 अंशानी (π/2) अवस्था विरलन होईल. / Rarefaction with a phase change of π/2 (by 90°)

4)विरलन होईल पण अवस्था बदलणार नाही. / Rarefaction with no phase change

When a compression of a longitudinal sound wave strikes a rigid wall, it reflects back as a compression with a phase change of 180 degrees or reversal, but compression remains compression (unlike a fixed end string where it inverts, sound pressure reflection at a rigid boundary reflects compression as compression). Wait, actually at a rigid wall, particle velocity has a node and pressure has an antinode, meaning a compression reflects as a compression.

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