Physics IGCSE grade 9

1. ULTRA SONIC
WAVES
By SHAMIK and ANINDA

2. SOUND
S o u n d i s c a u s e d b y v i b r a t i o n o f m o l e c u l e s i n a
medium
 We c a n h e a r o b j e c t s b e c a u s e w h e n t h e y v i b r a t e
they cause other particles to vibrate and those
vibrating particles hit our ear drum which
sends a signal to our brain which we perceive as
sound
By SHAMIK and ANINDA

3. SOUND RELATED
TERMS
S p e e d : S p e e d i s t h e d i sta n c e t rave l l e d b y
t h e wave i n u n i t t i m e ( S I u n i t : m /s )
Wave l e n gt h : t h e wave l e n gt h o f a wave o f
s o u n d ca n b e d ef i n e d a s t h e d i sta n c e
b e t we e n t h e c e nte rs o f 2 co n s e c u t i ve
co m p re s s i o n s ( S I u n i t : m e te rs )
By SHAMIK and ANINDA

4. • F re q u e n c y : f re q u e n c y i s t h e n o . o f wave s
p a s s i n g t ro u g h a g i ve n p i nt i n 1 s e c o n d ( S I
u n i t : H z ) .T h e re i s a re l at i o n b e t we e n
f re q u e n c y a n d wave l e n gt h t h at
c o r re s p o n d s to ; f re q u e n c y i s i nve rs e l y
p ro p o r t i o n a l to wave l e n gt h i . e . a s
f re q u e n c y r i s e s wave l e n gt h d e c re a s e s a n d
a s wave l e n gt h i n c re a s e s f re q u e n c y
d e c re a s e s
By SHAMIK and ANINDA

5. WHAT ARE ULTRA
 Humans can her sounds between
SONIC y o f 2 0 H z t o
t h e r a n g e f r e q u e n c WAVES
20,000 Hz
A n y n o i s e a b o v e t h e f r e q u e n c y o f
20,000 Hz is known as ultrasonic
sound while any sound
A n y n o i s e b e l o w 2 0 H z i s k n o w n a s
infrasound
By SHAMIK and ANINDA

6. USES OF ULTRA SONIC
SOUNDS
 Ultra sonic waves are used in SONAR( SOund
Navigation And Ranging). It is a device attached
to the hull of a boat to calculate the depth of
the sea. The device sends out ultrasonic waves
and the distance to the sea bed is calculated on
t h e b a s i s o f t h e t i m e t a ke n f o r t h e e c h o t o b e
received
I t i s u s e d t o c r e a t e a c c u r a t e i m a g e s o f t h e
h u m a n b o d y. I t i s u s e d d u r i n g s u r g e r i e s t o s c a n
damaged organs. When the wave is sent it
penetrates the skin and an image is made on
the basis of the echo
By SHAMIK and ANINDA

7.  Ultra sonic waves are used in cleaning very
small parts such as those in watches
 It is used to scan for defects such as small
cracks in metals. When ultra sonic waves are
aimed at metal most of it is blocked but where it
is able to pass there is a crack to allow the sound
to pass through that needs to be fixed
 It is used to make cuts to hard materials such as
glass
By SHAMIK and ANINDA

8. ECHOLOCATION
 In nature bats and dolphins use ultra sonic sounds to
help navigate and find objects in a method called
echolocation. In this method an animal sends out a
high pitched ultra sonic sound which bounces of other
objects and comes back in the form of an echo with
which the animal can hear and perceive information
such as distance shape and size and even what
exactly the object is. Dolphins use this method to
detect shoals of fish in the sea, while bats use it to
navigate and find insects in the dark
By SHAMIK and ANINDA

9. THANK YOU FOR YOUR
KIND ATTENTION
By SHAMIK and ANINDA