Echo
Echo
A Special Feature Of The Human Ear- Persistence Of Hearing
The human ear has a special feature. This is its property of persistence of hearing. When a given sound reaches the human ear and affects the ear drum, its effect ‘stays on’ in the ear drum for nearly 1/10th, i.e. 0.1 of a second. This helps us to get a ‘feeling of continuity’ while hearing one sound after another.
Echo
Let be a common experience that when we shout into a well or inside an empty hall, or inside a dome, we hear our own sound after a short time. It happens because our sound is reflected from the walls. When sound waves strikes a surface, they return back into the same medium. This phenomenon is called reflection, this is known as echo.
Relation between speed of sound, time of hearing echo and distance of reflecting body :
Let t be the time at which an echo is heard, d is the distance between the source of sound and the reflecting body and v is the speed of sound. The total distance travelled by the sound is 2d. Speed of sound, or
_1.jpg)
The sensation of sound last or presists in our brain for 0.1 s (1 /10 sec) even after the source of sound has stopped vibrating. Taking sound speed (v) to be 344 m/s.
Thus, for hearing distinct echoes, the minimum distance of the obstacle from the source of sound must be 17.2 m from the source.
Conditions for the formation of echoes :
Types of Echoes:
(i) Instantaneous echo: The echoes of sound of short duration is called instantaneous echo.
(ii) Syllabic echo: The echo of syllables of spoken words is called syllabi echo.
(iii) Successive echo : This echo is heard when sound is produced between two distance parallel rows of tall buildings or hills.
Echo is a type of : | |||
| Right Option : A | |||
| View Explanation | |||
A man stands at a distance of 225 m from a cliff. He fires a gun and heard the echo after 1.5 seconds. What will be the velocity to the sound ? | |||
| Right Option : B | |||
| View Explanation | |||
Which of the following are correct : (a) Echoes may be heard more than once due to successive multiple reflections. (b) To hear an echo, our distance from the reflecting surface should be atleast 17.2 m. (c) To hear an echo, our distance from the reflecting surface should be atleast 34.4 m. | |||
| Right Option : A | |||
| View Explanation | |||
Students / Parents Reviews [10]
It has a great methodology. Students here can get analysis to their test quickly.We can learn easily through PPTs and the testing methods are good. We know that where we have to practice
Barkha Arora
10thI have spent a wonderful time in Abhyas academy. It has made my reasoning more apt, English more stronger and Maths an interesting subject for me. It has given me a habbit of self studying
Yatharthi Sharma
10thMy experience was very good with Abhyas academy. I am studying here from 6th class and I am satisfied by its results in my life. I improved a lot here ahead of school syllabus.
Ayan Ghosh
8thMy experience with Abhyas is very good. I have learnt many things here like vedic maths and reasoning also. Teachers here first take our doubts and then there are assignments to verify our weak points.
Shivam Rana
7thAbout Abhyas metholodology the teachers are very nice and hardworking toward students.The Centre Head Mrs Anu Sethi is also a brilliant teacher.Abhyas has taught me how to overcome problems and has always taken my doubts and suppoeted me.
Shreya Shrivastava
8thAbhyas Methodology is very good. It is based on according to student and each child manages accordingly to its properly. Methodology has improved the abilities of students to shine them in future.
Manish Kumar
10thIt was good as the experience because as we had come here we had been improved in a such envirnment created here.Extra is taught which is beneficial for future.
Eshan Arora
8thMy experience with Abhyas academy is very good. I did not think that my every subject coming here will be so strong. The main thing is that the online tests had made me learn here more things.
Hiya Gupta
8thBeing a parent, I saw my daughter improvement in her studies by seeing a good result in all day to day compititive exam TMO, NSO, IEO etc and as well as studies. I have got a fruitful result from my daughter.
Prisha Gupta
8thA marvelous experience with Abhyas. I am glad to share that my ward has achieved more than enough at the Ambala ABHYAS centre. Years have passed on and more and more he has gained. May the centre flourish and develop day by day by the grace of God.
