PHYSICS & AERODYNAMICS

AJD10103UNIVERSITI KUALA LUMPUR

MALAYSIAN INSTITUTE OF AVIATION TECHNOLOGY

PREPARED BY :NUR AZNI SHAHIRA BT. MOHD SANUSI

531041152281 AVM 1

PREPARED FOR : MS. AZLINDA ABU BAKAR

SEMESTER JULY 2015

TOPIC : OPTICS ( LIGHT )

&WAVE MOTION AND SOUND

OPTICS ( LIGHT )

PROPERTIES OF LIGHT1) 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.

THE ELECTROMAGNETIC SPECTRUM

DISPERSION OF LIGHT1) 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.

COLOUR COMBINATION1) 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.

REFLECTION OF LIGHT1) 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.

CONCAVE MIRROR1) Concave mirror is a converging mirror due to its ability to

converge light.2) The applications of concave mirror :

Reflector – car headlights and torchlightsMagnified mirror – dentist’s mirror

CONVEX MIRROR1) 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.

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

REFRACTION OF LIGHT1) 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.

LAWS OF REFRACTION1) The incident ray, refracted ray and normal lie in the same plane.2) The ratio of is a constant, where i is the angle of incidence and r

is the angle of refraction.3) Refractive index, n = = 4) The above ratio is known as Snell’s Law.

CRITICAL ANGLE

1) When the angle of refraction is 90 , the angle ⁰of incidence is known as the critical angle.

TOTAL INTERNAL REFLECTION1) When the angle of incidence, i, exceeds the critical angle ,c ,

total internal reflection occurs.

LENSES1) Two types of lenses : Convex lens and

Concave lens2) 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) The real or virtual image can be found by using this formula :

= + u = distance of object from lensv = distance of image from lensf = focal length of lens

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

WAVE MOTION AND SOUND

MECHANICAL WAVES1) 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

TRANSVERSE WAVE1) 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.

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.

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.

WAVE CHARACTERISTICS

WAVE CHARACTERISTICS1) Amplitude, – maximum displacement from the mean position.2) Wavelength, – distance between two crest.3) Frequency, – number of wave crests that pass a point every

second.4) Velocity, – speed and direction that the wave crest itself is

moving.5) Relationship between wavelength, frequency and velocity.

=

INTERFERENCE WAVES1) 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).

STANDING WAVES1) 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.

SOUND1) 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

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, =

SOUND INTENSITY1) 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.

FREQUENCY1) The number of vibration

completed per second.2) f = , 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.

SOUND PROPAGATION1) Transmission and reception of sound : Sound, Medium and Detector.

DOPPLER EFFECT1) 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.

SOUND VIBRATION1) 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.

SPEED OF SOUND1) The speed at which the mechanical vibrations of sound travel in

an elastic medium.2) Varies – temperature and altitude.

MACH NUMBER

1) The ratio of the speed of the airplane to the speed of sound in the same atmospheric conditions.

2) Mach number =

RESONANCE1) 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.