The document discusses reflection of sound and how various devices use reflection of sound waves. It defines reflection of sound as sound bouncing back when it strikes a hard surface. It describes how a megaphone amplifies and directs sound by reflecting it, a stethoscope is used by doctors to listen to body sounds by reflecting them, and a soundboard in a large hall reflects sound to aid listening. Echoes occur when a sound reflects off a surface and the original sound and reflection can be heard separately if there is a time interval of at least one tenth of a second between them.

3. A MEGAPHONE
A BULB HORN
A STETHOSCOPE
A SOUNDBOARD

4. • The bouncing back of sound when it strikes a
hard surface is called reflection of sound
• Sound is reflected well from hard surfaces like
wall, a metal sheet, hard wood, and a cliff.
• Soft surfaces are bad reflectors of sound.
• Sound can be reflected from any surface
whether smooth or rough.

5. • The laws of reflection of light are obeyed
during the reflection of sound.
• The laws of reflection of sound:
• THE INCIDENT SOUND WAVE. THE REFLECTED
SOUND WAVE. AND THE NORMAL AT THE
POINT OF INCIDENCE, ALL LIE IN THE SAME
PLANE.
• THE ANGLE OF REFLECTION OF SOUND IS
ALWAYS EQUAL TO THE ANGLE OF INCIDENCE

6. • A MEGAPHONE is a cone shaped device of
amplifying and directing the voice of person who
speaks into it.

7. • A BULB HORN is a shaped wind instrument
which is used for signalling in vehicles.

8. • A STETHOSCOPE is a medical instrument used by
doctors for listening the sounds produced in
human body.

9. • A SOUNDBOARD is a concave board is a concave
board which is placed behind the speaker in large
halls for easy listening.

10. • The repetition of sound of sound caused by the
reflection of sound waves is called an echo.
• When a person shouts in a big hall we first hear
his original sound , after a little while, we hear a
reflected sound of shout.
• An echo is a simply reflected sound.
• We can hear the original and reflected sound
sound separately only if there is a time interval
of at least one tenth of sec.

11. • The minimum distance from a sound
reflecting surface to hear an echo is 17.2
metres(at 20 degree celcius).
• The distance will change with the temperature
of air.
• When the travels in water, then the minimum
distance for hearing an echo will be
different(because the peed of sound in water
is different).

12. • The persistence of sound in a big hall due to
repeated reflections from the walls, ceilling
and floor of the hall is called

13. A PROJECT BY :
TUSHAR
SARKATE

14. GUIDE OF THE PROJECT