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WavesLesson 1.1: Understanding waves

Lesson 1.2: Reflection of waves

Lesson 1.3: Refraction of Waves

Lesson 1.4: Diffraction Waves

Lesson 1.5: Interference of Waves

Lesson 1.6: Sound Waves

Lesson 1.7: Electromagnetic Waves

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1.1 Understanding Waves

a) Motion of waves

b) Propagation of wavesc) Type of wavesd) Wavefrontse) Wave profilef) Graph= Displacement vs (distance)(time)g) Wave speedh) Damping and resonance

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Waves

1.1 Understanding Waves

An oscillating or vibrating motion in which

a point or body moves back and forth

along a line about a fixed central point

produces waves

An oscillating or vibrating system acts asthe source of waves which transfer energy

from one point to another (without

transferring matter)

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A wave is a disturbance that transfersenergy between two points through

vibrations in athe two points medium,

without transferring matter between thetwo points.

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Examples of the waves:

a) Light waves are produced as a

result of vibrations of electrons in

an atoms.

b) Sound waves are produced byvibrating mechanical bodies such

as guitar strings or a tuning fork.

c) Water waves are produced by adisturbance (or vibration) on a still

water surface.

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Transverse Wave

Gelombang melintang

Dalam gelombang melintang, zarah zarah medium di anjakkanpada arah berserenjang dengan arah gerakkan gelombang.

A transverse wave is a wave in whichparticles of the medium move in a directionperpendicular to the direction which the wavemoves.

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Transverse waves on a string are another example. The string is

displaced up and down as the wave travels from left to right, but the string

itself does not experience any net motion.

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Example of a

longitudinal wave.

Contoh gelombang membujur

Penala bunyi yang bergetar memampatkan udara dalam

paip pergi balik ke arah yang selari dengan arah

pemindahan tenaga. Bunyi adalah gelombangmembujur.

A vibrating tuning fork will force air within a pipe tobegin vibrating back and forth in a direction parallel tothe energy transport; sound is a longitudinal wave

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Examples which illustrate the definition

Have you ever "done the wave" as part of a large crowd at a football or baseball game? A group of people jumps up

and sits back down, some nearby people see them and they jump up, some people further away follow suit and pretty

soon you have a wave travelling around the stadium. The wave is the disturbance (people jumping up and sitting back

down), and it travels around the stadium. However, none of the individual people the stadium are carried around with

the wave as it travels - theyall remain at their seats.

Longitudinal sound waves in air behave in much the same way. As the

wave passes through, the particles in the air oscillate back and forth about

their equilibrium positions but it is the disturbance which travels, not the

individual particles in the medium

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An electromagnetic wave is a wave which iscapable of transmitting its energy through avacuum (i.e., empty space). Electromagneticwaves are produced by the vibration ofelectrons within atoms on the Sun's surface.

Gelombang elektromagnetik adalah gelombang yang mampumemindahkan tenaganya menerusi vakum. Gelombangelektromagnetik di hasilkan oleh getaran elektron dalam atomdi permukaan matahari.

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Wavefronts

- is an imaginary line

- A wavefront is a line that joints all the

points vibrating in phase, such as a line

passing through similar wave crests.

- Points in a wave are in phase if they

vibrate in the same direction with the

same displacement.

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When a wave is present in a medium (that is, whenthere is a disturbance moving through a medium),the individual particles of the medium are onlytemporarily displaced from their rest position

When a wave is present in a medium (that is, whenthere is a disturbance moving through a medium),the individual particles of the medium are onlytemporarily displaced from their rest position

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WAVE FRONTWAVE FRONT

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Check your understanding

1) If the vibration of a wave are at right angles to the

direction of the wave, it is called a _____________wave.

An example of this type of wave is ____________.

2) If the vibration of a wave are along the direction ofthe wave, it is called a ___________ wave.

An example of this type of wave is _______________.

3) A wave carries energy from ____________ to

_______________, without any transferring of the

_________________.

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Equilibrium position is.

One complete oscillation has occurred when

the bob has moved through positions A-B-C-B-A, that is when it has returned to its startingposition and is moving in the same direction.

Amplitude, a of an oscillation is the maximumdisplacement from the mean position.

Period, T of the oscillation is the time taken tocomplete one oscillation.

Frequency, fof the oscillation is the number ofcomplete oscillation made in one second.

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Oscillating System

Oscillating system consists of:

Amplitude

Period

Frequency

Wavelength

Wave speed

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Displacement Time Graph

Peak

Period

s/cm

t/s

Amplitude, a

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Displacement Distance Graph

Peak

Wavelength

s/cm

x/cm

Amplitude, a

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Frequency, f

Numbers of

oscillation in one

second.

Unit : Hertz (Hz)

f =1T

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A

B

C

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Wave Speed, v

Wave speed, vdepends on wavelength, and frequency, f.

Wave speed, v = f

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Wavelength, is the horizontal distance

between two successive equivalent pointson the wave.

Wave speed, v is the distance travelled by

a wave in one second in the direction ofpropagation.

Wave speed, v is the distance moved by acrest in one second.

Wave speed , v = f

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Check your understanding

1) The wavelength of a wave is the

______________ between two successive______________ or ______________.

2) The frequency is the number of________________ oscillations made in

_____________ second. The unit for

frequency is _______________.

3) The velocity of wave is equal to

______________ multiplied by

_______________.

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The time taken for a vibrating system to make a

complete oscillation is known as

______________.

The number of complete oscillation made by a

vibrating system is known as

___________________.

The distance traveled by a wave in one secondis known as ______________.

If the of an oscillating system is 0.2s and itswavelength is 60 cm, what is the velocity of the

wave formed by this oscillating system?

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Damping is said to have occurred in

an oscillating system when the

system loses energy to thesurroundings, usually in the form of

heat energy.