# Waves And Sounds – Wave Parameters

## Waves and Sounds

A Wave is a disturbance which travels through matter or space and carries energy from one point to another without permanently displacing the particles of matter. The matter through which wave can pass is called medium. Examples are Solids, Liquids, and Gases. Sound travels fastest in solids, faster in liquids, and fast in gases.

WAVE MOTION is a means of transferring energy in a medium. A CREST is the highest point of the wave. TROUGH is the lowest point of the wave.

### Wave Parameters

• AMPLITUDE: This is the maximum displacement of the particle of the medium from its rest point. The unit is Meter (m).
• WAVELENGTH: This is the distance between two successive troughs or crests in a wave. The unit is Meter (m) and the symbol is Lambda ()
• PERIOD: This is the time for the wave to complete one cycle. The unit is Second (s) and the symbol is (T).
• FREQUENCY: This is the number of cycles made by the wave in one second. The unit is Hertz (H3) or per second (51). The symbol is f.
• SPEED: This is the distance covered by the wave in one second. The unit is meter per second (m/s) and the symbol is V.
• PHASE: Particles are said to be in phase if they are at the same distance from their rest positions, having the same velocity and moving in the same direction in a medium.
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### Classes of Waves

• MECHANICAL WAVES: These are waves that require material mediums for their propagation. Examples are Soundwave, Water wave, Shockwave, Waves in a spring and string (rope)
• ELECTROMAGNETIC WAVES: These are waves that require no medium for their propagation. They move through space or vacuum. Examples are Light waves, X-rays, Radio waves, Microwaves etc…

### Uses of Electromagnetic Waves

1. Vision
2. Communication
3. Photography
4. X-rays:
• It displays the picture of a broken bone in the body.
• For destroying malignant growth in the body.
• For detecting cracks and flaws in the internal structure of metals.
• For detecting leakages in underground pipes.
• For detecting hidden metallic objects at the airports and banks.

## Types of Waves

• TRANSVERSE WAVES: These are waves that travel perpendicular to the direction of vibration of particles of the medium. Examples are Water waves, Light waves, X-rays, Radio waves, Microwaves, Wave in a string or rope etc…
• LONGITUDINAL WAVES: These are waves that travel in the same direction as the particles of the medium. Examples are Soundwave, Shockwaves, Wave in a spring.

• Réflexion
• Refraction
• Diffraction
• Interference
• Polarization

### Interference

This is the effect produced when two waves of the same frequency, wavelength, and amplitude traveling in the same direction in a medium pass through the same point. The waves are said to be COHERENT. For waves to be coherent, they must:

• Have the same Wavelength
• Have the same Amplitude
• Have the same Frequency
• Travel in the same Direction
• Have a constant phase difference (be in phase)
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### Superposition

This is the coming together of two or more waves at the same point at the same time in a medium.

#### Principles of Superposition

States that when two or more waves passes any point at the same time in a medium, the resultant displacement at the point is equal to the sum of the individual displacement due to each of the waves.

The result of the superposition of two or more waves is called interference.

### Types of Interference

• CONSTRUCTIVE INTERFERENCE: This is a type of interference that occurs when the superposition of identical waves result in an increased disturbance.
• DESTRUCTIVE INTERFERENCE: This occurs when the resultant effect of two identical waves result in their cancellation or they totally cancel the effect of each other. (Zero or reduced disturbance)

### Progressive or Travelling Wave

This is a wave which continues to spread out transferring energy from the source of the disturbance.

### Standing or Stationery Wave

This is the wave produced when two equal progressive waves of equal amplitude and frequency traveling in opposite directions are superposed.

### Sound Waves

A sound is a form of energy produced by vibrating objects. The speed of sound in air depends on temperature. If the temperature increases, the speed of sound increases. Sound waves cannot travel through a vacuum because there are no particles to collide with and they do not undergo polarization.

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ECHO is a sound heard after the reflection of sound from a plain surface.

### Uses of Echo Sounding

• It is a method used to determine the speed of sound in air.
• It can be used to determine the depth of the sea.
• Also used to explore for gas and oil.

Underground sound systems (Sonar) are used to detect underwater objects like fishes, submarines etc…

• AUDIBLE SOUND is the sound we can hear. (Ranges between 20HZ – 20KHZ)
• ULTRASOUNDS are sounds with higher frequencies than the audible sound. (Its frequency is more than 20KHZ)
• INFRASOUNDS are sounds with a frequency below the audible frequency range. (Its frequency is below 20HZ i.e. 0 – 19)

We cannot hear both Infrasound and Ultrasound.

### Properties of Sound Waves

1. Pitch: Use to know low or high sounds.
2. Timber/quality: Use to know the quality of the sound.
3. Loudness: To detect the loudness.
4. Intensity: Use to know the energy of that sound.
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