INTERFERENCE OF LIGHT Nodal line

Antinodal line

When crest superposed crest or trough superposed trough, constructive interference has occurred.

Constructive interference Bright fringe

When crest superposed trough destructive ,interference has occurred

Bright fringe (produced by constructive interference) interference)

Dark fringe (produced by destructive interference)

screen

Young double slit

Laser pen

Destructive interference Dark fringe

INTERFERENCE OF LIGHT WAVE

(Dwicelah Young) Screen Young Double slit

x Bright finge Dark fringe

Dark fringe

Bright fringe

Dark fringe

Bright fringe

Dark fringe

Bright fringe

Dark fringe

a x Bright fringe

Dark fringe

x Bright fringe Dark fringe

D

wavelength of light λ = ax D

CONDITION DIFFRACTION OR INTERFERENCE OF WAVE TO OCCUR:

USED MONOCHROMATIC LIGHT SOURCE WHICH has only one wavelength, λ.

INTERFERENCE OF LIGHT PATTERN (WHICH FORM ON THE SCREEN)

Laser pen

27mm x x x x 4 x= 27mm

x= 27 4

Bright fringe Dark fringe

λ = ax D

INTERFERENCE OF SOUND WAVE Loud sound

x Weak Sound Loud sound

SPEAKER 1

CONDITION INTERFERENCE OF SOUND WAVE TO OCCUR:-

2 sources must be coherentcoherent mean 2 sources have same frequency, same in phase and same wavelength.

a x Weak Sound Loud sound

x Weak sound Loud sound

D

λ = ax D

Loudness and Pitch.

LOUDNESS (Kekuatan bunyi)

Loudness of the sound is

SPEAKER 2

The loudness of sound depends on the amplitude of the wave.

The bigger the amplitude, the louder the sound.

PITCH (Kelangsingan bunyi)

The pitch of sound (how high the note is)depends on the frequency of the wave.

The higher the frequency, the higher the pitch.

.

Below is a picture of a sound wavewhich has been changed into alternating current by a microphone and displayed on a CRO.

If the sound is made louder and with a higher pitch,the shape of the wave changes as shown below.

The amplitude has got bigger because the sound is louder.The frequency has increased(there are more complete waves in the same time)because the sound has a higher pitch.

 

 

Echo(gelombang bunyi yang terpantul/gema)

Sound which has been reflected is called an echo.As with other waves, sound reflection best occurs from flat, hard surfaces.

T

T

Still remember?

f = 1/T

A boat on the sea can send a beam of ultrasound down to the sea floorwhere it is reflected back upwards to a detector on the boat.

sonar

d d speed,v = 2ddistance/ttime taken

Ultrasound (sonar) can be used by fishing boats to find fishsince a shoal of fish between the boat and the sea floorwill return the echo more quickly.