Light Wave and Sound Wave

1. PHYSICS &
AERODYNAMICS
AJD10103
UNIVERSITI KUALA LUMPUR
MALAYSIAN INSTITUTE OF AVIATION TECHNOLOGY
PREPARED BY :
NUR AZNI SHAHIRA BT. MOHD SANUSI
53104115228
1 AVM 1
PREPARED FOR :
MS. AZLINDA ABU BAKAR
SEMESTER JULY 2015
TOPIC :
OPTICS ( LIGHT )
&
WAVE MOTION AND SOUND

2. OPTICS ( LIGHT )

3. PROPERTIES OF LIGHT
1) Light travels in straight lines.
2) Light travels very fast – around 300,000 kilometres per seconds.
3) All electromagnetic waves travel at the same speed. The speed
of light is 300,000,000 m/s.

4. THE ELECTROMAGNETIC SPECTRUM

5. DISPERSION OF LIGHT
1) Dispersion of light can be defined as the separation of a visible
light beam into its constituent colors.
2) For example red, oranges, yellow, green, blue, indigo, violet
colors are obtained when a white light beam is dispersed.
3) It happens when a light beam passes through a dispersive
medium such as glass prism.
4) When the light passes from
one medium to another, the
light will refracted. So, the
least refracted is red and the
most refracted is violet.

6. COLOUR COMBINATION
1) Objects appear coloured because their
surface absorb some of the
frequencies and reflect others.
2) Red filter will only allow light with the
longer wavelengths associated with the
colour red to pass through.
3) Red, green and blue are known as light
primary colours as they cannot be
created.
4) Secondary colours can be created by
mixing two primary colours.

7. REFLECTION OF LIGHT
1) Reflection of light occurs when light falls on a surface and is
reflected by the surface.
2) The law of reflection :
 The angle of incidence, i = The angle of reflection, r
 The incident ray, reflected ray and normal all lie in the same
plane.

8. CONCAVE MIRROR
1) Concave mirror is a converging mirror due to its ability to
converge light.
2) The applications of concave mirror :
Reflector – car headlights and torchlights
Magnified mirror – dentist’s mirror

9. CONVEX MIRROR
1) Convex mirror is a diverging mirror
due to its ability to diverge light.
2) The applications of convex mirror :
Blind corner mirror – to widen
the field of view.

10. CURVED MIRRORS
 Principle axis, P – line passing the centre.
 Centre of curvature, C – centre of the mirror.
 Principal focus, F – midway point between P and C.
 Radius of curvature, R – distance between P and C.
 Focal length, f – distance between P to focal point. R = 2f

11. REFRACTION OF LIGHT
1) Refraction of light is a phenomenon
where the direction of light is changed
when it passes through two materials
of different optical densities.
2) Light travels faster in optically less
dense medium than in optically denser
medium.
3) It caused by :
A change in the speed of light as
it passes through two materials of
different optical densities.
A change in the direction at the
boundary between the two
materials.

12. LAWS OF REFRACTION
1) The incident ray, refracted ray and normal lie in the same plane.
2) The ratio of
sin 𝑖
sin 𝑟
is a constant, where i is the angle of incidence
and r is the angle of refraction.
3) Refractive index, n =
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝑣𝑎𝑐𝑢𝑢𝑚/𝑎𝑖𝑟
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝑎 𝑚𝑒𝑑𝑖𝑢𝑚
=
sin 𝑖
sin 𝑟
4) The above ratio is known as Snell’s Law.

13. CRITICAL ANGLE
1) When the angle of
refraction is 90⁰, the angle
of incidence is known as
the critical angle.

14. TOTAL INTERNAL REFLECTION
1) When the angle of incidence, i, exceeds the critical angle ,c ,
total internal reflection occurs.

15. LENSES
1) Two types of lenses : Convex lens and
Concave lens
2) Focal point, F – point where all parallel
rays converge after being refracted.
3) Focal length, f – distance between the
optical centre and the focal point.
4) Optical centre, O – centre point of the
lens.
5) Calculation of power
Power =
1
𝑓

16. 1) The real or virtual image can be found by using this formula :
1
𝑓
=
1
𝑢
+
1
𝑣
u = distance of object from lens
v = distance of image from lens
f = focal length of lens

17. QUANTITY POSTIVE NEGATIVE
FOCAL LENGTH, f CONCAVE LENS CONVEX LENS
OBJECT DISTANCE, p REAL OBJECT VIRTUAL OBJECT
IMAGE DISTANCE, q REAL IMAGE VIRTUAL IMAGE
MAGNIFICATION, m UPRIGHT IMAGE INVERTED IMAGE
HEIGHT, h UPRIGHT IMAGE INVERTED IMAGE

18. WAVE MOTION AND SOUND

19. MECHANICAL WAVES
1) Waves is a disturbance that travels through
space or a medium in a series of
oscillations.
2) Energy can travel by particle and wave.
3) The source of a wave is a vibration or
oscillation.
4) Waves transfer energy from one point to
another.
5) Energy is transferred without the medium
being transferred.
6) Two types of mechanical waves :
Transverse wave and Longitudinal wave

20. TRANSVERSE WAVE
1) A wave in which the vibration
of particles in the medium is at
right angle to the direction of
propagation of the wave.
2) The particles in the medium is
displaced in an up-and-down
position which is perpendicular
to the direction of the
propagation of the waves.

21. LONGITUDINAL WAVE
1) A wave in which the vibration of particles in the medium is
parallel to the direction of propagation of the wave.
2) The particles in the medium is oscillating to and fro, parallel
with the direction of the propagation of the waves.

22. WATER WAVES
1) Water waves are an example of
waves that involve combination
of longitudinal wave and
transverse wave.
2) The particles travels in
clockwise circles.
3) The radius of circles decreases
and the depth of water
increases.

23. WAVE CHARACTERISTICS

24. WAVE CHARACTERISTICS
1) Amplitude, 𝛼 – maximum displacement from the mean position.
2) Wavelength, 𝜆 – distance between two crest.
3) Frequency, 𝜔 – number of wave crests that pass a point every
second.
4) Velocity, 𝜈 – speed and direction that the wave crest itself is
moving.
5) Relationship between wavelength, frequency and velocity.
 𝜈 = 𝜆𝜔

25. INTERFERENCE WAVES
1) Interference – effect produced
when two or more waves meet at
the same place and interact.
2) Constructive interference – waves
arrive at a particular place in
phase (crest meets crest, trough
meets trough).
3) Destructive interference – waves
arrive at a particular place out of
phase (crest meets trough).

26. STANDING WAVES
1) Standing waves (stationary waves) –
occur in wires that are tightly stretched
between two points.
2) Transverse waves travel to the end and
reflected back when the wires being
plucked or caused to vibrate.
3) As the waves cross each other in their
travel backwards and forwards along
the wire, a standing wave pattern is
formed.
4) Nodes – points of no displacement.
5) Anti-nodes – midway between every
consecutive nodal point are points that
undergo maximum displacement.

27. SOUND
1) Sound – energy that produced when
an object vibrates causing the
surrounding air particles to vibrate
also.
2) Travels through air or other mediums
(longitudinal waves).
3) Sound waves (acoustic waves) –
regions of high pressure
(compression) and low pressure
(rarefaction).
4) Compression – region where
molecules gathered closely together.
5) Rarefaction – region where molecules
move apart

28. 1) Speed of sound depends on the medium
which it travels. Sounds cannot travel
through vacuum. Its speed is greater in
solids than in liquids or gasses –
vibration is much easier to transmit with
materials having closely packed
molecules.
2) Speed of sounds increases when the
temperature of air increases. Measuring
aircraft speed will varies at different
altitude level.
 Speed of sound, 𝛼 = 𝑅𝑇

29. SOUND INTENSITY
1) Determined – amplitude of
sound wave.
2) The higher the amplitude, the
higher the sound.
3) Measured in decibels (dB).
4) Ratio of one sound to another.
5) 1 dB the smallest change in
sound intensity that the human
ear can detect.

30. FREQUENCY
1) The number of vibration
completed per second.
2) f =
1
𝑡
, t = time (s).
3) Unit Hertz (Hz).
4) The higher the sound, the higher
the pitch.
5) A high pitch sound is from a high
frequency note.

31. SOUND PROPAGATION
1) Transmission and reception of sound : Sound, Medium and
Detector.

32. DOPPLER EFFECT
1) Doppler effect – change in
frequency which occurs
when the source that is
emitting the sound waves is
moving.
2) The apparent rise in the
pitch/frequency of a sound
as its source approaches
the hearer & the decrease
in pitch as the source
moves away.

33. SOUND VIBRATION
1) Causes wave which radiate out
from their source at the speed of
sound.
2) Aircraft moves less than speed
of sound, the sound moves
ahead of the aircraft.
3) Aircraft flies at the speed of
sound produces shock waves.

34. SPEED OF SOUND
1) The speed at which the mechanical vibrations of sound travel in
an elastic medium.
2) Varies – temperature and altitude.

35. MACH NUMBER
1) The ratio of the speed of the airplane to the speed of sound in
the same atmospheric conditions.
2) Mach number =
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑎𝑖𝑟𝑐𝑟𝑎𝑓𝑡
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑠𝑜𝑢𝑛𝑑

36. RESONANCE
1) A system oscillates
at its natural
frequency when no
external force is
applied to it.
2) The system is said
to be at resonance
when it is driven at
its own natural
frequency.