Question

prove that the minimum distance required to hear an echo is 1/20 part of the magnitude of the velocity of sound in air prove
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Answer 1

Answer:

Explanation:

. The persistence of hearing for human ears is 0.1 second. This means that you can hear two sound waves clearly, if the time interval between the two sounds is at least 0.1 s. Thus, the minimum time gap between the original sound and an echo must be 0.1 s.

2. The above criterion can be satisfied only when the distance between the source of sound and the reflecting surface would satisfy the following equation:

Since, t = 0.1 second, then d = [v × 0.1] / 2 = v/20

Thus the minimum distance required to hear an echo is 1/20 th part of the magnitude of the velocity of sound in air. If you consider the velocity of sound as 344 m s–1, the minimum distance required to hear an echo is 17.2 m.

 

2. Applications of echo

·                 Some animals communicate with each other over long distances and also locate objects by sending the sound signals and receiving the echo as reflected from the targets.

·                 The principle of echo is used in obstetric ultrasonography, which is used to create real-time visual images of the developing embryo or fetus in the mother’s uterus. This is a safe testing tool, as it does not use any harmful radiations.

·                 Echo is used to determine the velocity of sound waves in any medium.

Answer 2

Answer:

Compounds can be covalent or ionic. ... In ionic compounds, electrons are completely transferred from one atom to another so that a cation—positively charged ion—and an anion—negatively charged ion—form. The strong electrostatic attraction between adjacent cations and anions is known as an ionic bond.

Explanation: