5.6 INTERFERENCE OF WAVES

CHAPTER 5
WAVES

5.6 INTERFERENCE OF WAVES

TEXT BOOK : PAGE 210 - 219

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Only one ripple CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES
Dua gelombang membulat
yang dihasilkan bertindih What happens when the two
waves are in superposition?
atau bersuperposisi.

When two waves interrupting CHAPTER 5 WAVES
(overlapping) each other, 5.6 INTERFERENCE OF WAVES
some patterns formed.
This phenomenon is due
to superposition of two

waves.

Superposition of two waves: Look at 2 single wavefronts CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

When crest meet with When two crests
trough, the amplitude (peaks) of waves meet
become lower or flat.
each other, the
amplitude become
higher or maximum.

Separated the two waves
to see clearer the effect

of superposition.

The red is the result
of the superposition.

Superposition of two waves: Look at 2 single wavefronts CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

When two crests
(peaks) of waves meet

each other, the
amplitude become
higher or maximum.

Separated the two waves
to see clearer the effect

of superposition.

The red is the result
of the superposition.

Superposition of two waves: Look at 2 single wavefronts CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES
When crest meet with
trough, the amplitude
become lower or flat.

Separated the two waves
to see clearer the effect

of superposition.

The red is the result
of the superposition.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

The principle of superposition states that when two waves
overlap, the resultant displacement is the sum of the individual
displacements of the two waves.

Displacement = amplitude

Superposition simulation Superposisi berlaku di
atas dan bawah juga

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Interference with Coherent Source of Waves

Interference of waves is the superposition of two or more waves from a
coherent source of waves.

Coherent means same frequency
and phase difference is constant

Superposition of waves produces constructive (membina)
interference and destructive (memusnah) interference.

The principle of superposition states that when two waves CHAPTER 5 WAVES
overlap, the resultant displacement is the sum of the individual 5.6 INTERFERENCE OF WAVES
displacements of the two waves.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

The principle of superposition states that when two waves
overlap, the resultant displacement is the sum of the individual
displacements of the two waves.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Interference of Waves

To get 2 coherent waves, we can The wave spreads after going through
use one source of wave to go the 2 slits and produces 2 coherent
through two slits. waves, then interference occurred.

Diffraction (pembelauan)
occurred when wave spread

from each splits

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Interference of Waves

One slit (gap), 2 slits (2 gaps),
wave spreading after the slit, 2 diffracted waves overlapping
causing interference occurred.
diffraction occurred.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Interference of Water Waves

Interference of Light Waves CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES
Diffracted light waves that
appear from the double-slit
are coherent.

Superposition of waves from the double-slit.

Constructive interference produces bright
fringes while destructive interference
produces dark fringes.

Interference pattern formed on the screen
with light.

Interference of Light Waves CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES
Diffracted light waves that
appear from the double-slit
are coherent.

Superposition of waves from the double-slit.

Constructive interference produces bright
fringes while destructive interference
produces dark fringes.

Interference pattern formed on the screen
with light.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Interference of Sound Waves

Sound waves cannot be seen.
Observer can only hear loud sounds in
constructive interference regions and
soft sound in destructive interference
regions.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Drawing Patterns of Wave Interference

Points P and Q are antinodes, the points where constructive interference occurs.
Point R is a node, the point where destructive interference occurs.

Antinodes
(constructive)

Antinodes
(constructive)

Node
(destructive)

Node
(destructive)

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Relationship between Variables of Interference of Waves CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Longer
wavelength

Longer distance
between

source/slitss

Relationship between Variables of Interference of Waves CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

From Pattern 1 and Pattern 2: (b) What is the relationship
(a) Determine the constant variable. between x and a?

D, distance between source and a higher, x higher
fringes/screen

Relationship between Variables of Interference of Waves CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

From Pattern 2 and Pattern 3:
(a) Determine the constant variable.

Distance between two sources

(b) Compare the wavelength, λ.
wavelength, λ in pattern 3 is
longer than pattern 2

(c) What is the relationship between x and λ?
λ higher, x higher.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

We can interrelate the four variables:

2 crests or 2 Effect of CHAPTER 5 WAVES
trough meet superposition 5.6 INTERFERENCE OF WAVES
of 2 coherent
Crest and
waves trough meet

Constructive Destructive
Interference Interference

Resultant Formula Resultant
amplitude is amplitude is
maximum
λ = zero

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Applications of Interference of Waves in Daily Life

Luan bebuli menjana gelombang air
yang berinterferens secara
memusnah dengan gelombang air
yang dihasilkan oleh haluan kapal.
Hal ini menjadikan air di sekitar
kapal lebih tenang dan
mengurangkan seretan air

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Applications of Interference of Waves in Daily Life

Salutan pada permukaan kanta anti-pantulan
menyebabkan cahaya terpantul berinterferens
secara memusnah. Salutan ini membantu
menjadikan penglihatan lebih jelas dan
mengelakkan pembentukan imej pada kanta cermin
mata.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

Applications of Interference of Waves in Daily Life

Sistem mikrofon dan pemancar pada fon
kepala yang digunakan di kapal terbang
menghasilkan gelombang bunyi yang
berinterferens secara memusnah dengan
bunyi sekeliling yang hingar

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

(a) Diffraction
(the light waves spreading)

(b) Superposition produces bright
and dark fringes
(c) Construction interference
produces bright fringes.
Destructive interference produces
dark fringes.

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

(d) λ = (0.00030)(0.0046)
2.5
λ = 5.52 x 10-7 m

CHAPTER 5 WAVES
5.6 INTERFERENCE OF WAVES

THE END