Phycis Form 5: Chapter 1.4 Diffraction of Waves

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PHYSICS 1.4 Diffraction of Waves Prepared by: Qhaiyum Budi Nadzri Aimran Abdullah Azam

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Our presentation ! :D Physics Form 5: Chapter 1.4 Diffraction of Waves ..

Transcript of Phycis Form 5: Chapter 1.4 Diffraction of Waves

Page 1: Phycis Form 5: Chapter 1.4 Diffraction of Waves

PHYSICS

1.4 Diffraction of Waves

Prepared by:

QhaiyumBudiNadzriAimranAbdullah Azam

Page 2: Phycis Form 5: Chapter 1.4 Diffraction of Waves

Definition of Diffraction

Diffraction is the spreading of waves that happens when it passes through a narrow opening or when it passes round a small obstacle along it’s path.

Page 3: Phycis Form 5: Chapter 1.4 Diffraction of Waves

Characteristics of Diffraction

When diffraction occurs:

i. Wave direction changes.ii. Wave velocity, ν, changes.iii. Wavelength, λ, is unchanged.iv. Frequency, ƒ, is unchanged.v. Speed unchanged.

The amplitude, а, of the diffracted wave is smaller compared to that of the incident wave, as the wave energy is spread out over a larger surface.

Page 4: Phycis Form 5: Chapter 1.4 Diffraction of Waves

Diffraction of Water Waves

Waves are diffracted more if the

i. Opening is narrow.ii. Obstacle is small.

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When the width of the opening is smaller than the wavelength, λ, the wave will be well diffracted.

When the opening is very narrow, the wave is very well diffracted.

The size of the opening is too big, the wave is not well diffracted.

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When the size of the obstacle is smaller than the wavelength, λ, the wave will be well diffracted.

The size of the obstacle is small, the waves are well diffracted.

The size of the obstacle is too big, the waves are not well

diffracted.

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Diffraction of Light Waves

Light is diffracted when it passes through a very narrow opening such as a pin-hole or a slit.The diffraction pattern produced by light consists of a central bright fringe and a few smaller bright fringes, separated by dark fringes.

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Diffraction of Sound Waves

Sound can be diffracted as it passes through window slits or wall corners.

The cleaner standing at the point where he cannot see the radio but he can hear the sound

from it due to diffraction of sound waves by the wall corner.

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Applications in Everyday Life

Sea-walls in a harbour jetty:

i. Strong concrete walls are usually built in the sea near a harbour jetty to protect the boats from damage caused by strong waves.

ii. When strong waves rush towards the harbour jetty, the concrete barriers reflect some of the waves and allow others to diffract through the opening between the barriers.

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