Reflection of sound class 10 | 10th class physics | punjab, kpk, federal, balochistan board

Echo or reflection of sound sabaq in urdu or echo physics wallah subject 10th class physics wallah subject 10th class chapter 13 electrostatics.
Queries solved in this video
1. what is echo ?
2. what is reflection of sound?
3. what is difference between echo or reflection of sound?
11.3 REFLECTION (ECHO) OF SOUND
When we clap or shout near a reflecting surface such as a tall
building or a mountain, we hear the same sound again a little
later. What causes this? This sound which we hear is called
an echo and is a result of reflection of sound from the surface.
When sound is incident on the surface of a medium it
bounces back into the first medium. This phenomenon is
called echo or reflection of sound.
The sensation of sound persists in our brain for about 0.1 s.
To hear a clear echo, the time interval between our sound
and the reflected sound must be at least 0.1 s. If we consider
-1 speed of sound to be 340 ms at a normal temperature in air,
we will hear the echo after 0.1 s. The total distance covered
by the sound from the point of generation to the reflecting
-1 surface and back should be at least 340 m s × 0.1 s = 34.0 m.
Thus, for hearing distinct echoes, the minimum distance of
the obstacle from the source of sound must be half of this
distance, i.e., 17 m. Echoes may be heard more than once due
to successive or multiple reflections.
Activity 11.3: Take two identical plastic pipes of suitable
length, as shown in Fig. 11.10. (We can make the pipes using
chart paper).
 Arrange the pipes on a table near a wall.
 Place a clock near the open end of one of the pipes and
try to hear the sound of the clock through the other pipe.
 Adjust the position of the pipes so that you can hear
the sound of the clock clearly.
 Now, measure the angles of incidence and reflection
and see the relationship between the angles.
SUMMARY
Sound is produced by a vibrating body. It travels in the medium from one place to
another in the form of compressional waves.
Loudness is a feature of sound by which a loud and a faint sound can be distinguished.
It depends upon the amplitude, surface area and distance from the vibrating body.
  ur ears are called noise and the sounds having
pleasant effect on our ears are called musical sounds.
Noise pollution has become a major issue of concern in some big cities. Any form of
sound which disturbs the normal functioning of any natural ecosystem or some
human community is the cause of noise pollution.
 Noise pollution can be reduced to acceptable level by replacing the rusty noisy
machinery with environment friendly machinery and equipments, putting sound￾reducing barriers, or using hearing protection devices.
 The technique or method used to absorb undesirable sound energy by soft and
porous surfaces is called acoustic protection. This can be done by using soft, rough
and porous materials.
11.2. What is the effect of the medium on the speed of sound? In which medium sound
travels more faster: air, solid or liquid? Justify your answer.
11.3. How can you prove the mechanical nature of sound by a simple experiment?
11.4. What do you understand by the longitudinal wave? Describe the longitudinal
nature of sound waves.
11.5. Sound is a form of wave. List at least three reasons to support the idea that sound is a wave.
11.6. We know that waves manifest phenomenon of reflection, refraction and
diffraction. Does sound also manifest these characteristics?
11.7. What is the difference between the loudness and intensity of sound? Derive the
relationship between the two.
11.8. On what factors does the loudness of sound depend?
11.9. What do you mean by the term intensity level of the sound? Name and define the
unit of intensity level of sound.
11.10. What are the units of loudness? Why do we use logarithmic scale to describe the
range of the sound intensities we hear?
11.11. What is difference between frequency and pitch? Describe their relationship
graphically.
11.12. Describe the effect of change in amplitude on loudness and the effect of change in
frequency on pitch of sound.
11.13. If the pitch of sound is increased, what are the changes in the following?
a. the frequency b. the wavelength
c. the wave velocity d. the amplitude of the wave
11.14. If we clap or speak in front of a building while standing at a particular distance, we
rehear our sound after sometime. Can you explain how does this happen?
11.15. What is the audible frequency range for human ear? Does this range vary with the
age of people? Explain.
11.16. Explain that noise is a nuisance.
11.17. Describe the importance of acoustic protection.
11.18. What are the uses of ultrasound in medicine?

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[hamzaJamil-hb]

After a long time struggle I got the right person❤

[sughrabashir]

Wel explained..youtube k lectures mn echo or reflection ka difference sirf ap k lecture mn mila

[sadprincess]

Mashallah 💖
May Allah bless you sir 😊😊

[sadprincess]

Well explained in little time mashallah 😊😊

[Hamza-ngYg]

Finally after long time i got the right person ❤😊🎉🎉🎉

[Online_Logic]

Really really amazing dashing and fabulous ❤️❤️❤️❤️

[fasihullisan]

since the minimum time for echo is 0.1 seconds, then why echo is heard sooner in water than air ?

[famvlogs]

Sir but in empty room that is in majorit a few meters kr even in washroom the distance between us and wall is less than 17 meters.why do then we hear echo there

[fizzajabeen]

Aoa...have u notes of conceptual questions for 10th class

[abdulhannan]

how much distance is required to produce more than 1 echo such as 2, 3, 4 etc ?

[saniya]

Sir, JB hm Khali room ma JB awaz lagte hn tu wo awaz ghonjti hai. But JB room Khali nhi hota tu kyun awaz itna nhi ghnjti ?

[beeru]

Sir maine composite supplementary exams diye thay 2019 mai jiska January 2020 mai result aya. Inn maise 4 papers Chemistry( part 1 and part 2) aur Physics( part 1 and part2) mai absent rhi aur absent pae bhi fail ke hi rules lagtay hain. Ab maine 4 papers dene thay.Kia ye pass krdiye gaye hain?
Kionke ye 12 maise 4 fail hain
Aur 40% se kam failed hain

[misbahkhan]

Sir what is the difference between echo and reverberation