Medium of Propagation

Sound is a sequence of waves of pressure which propagates through compressible media such as air or water. During their propagation, waves can be reflected, refracted, or attentuated by the medium. The purpose of this experiment is to examine what effect the characteristics of the medium have on sound.

Ground Wave or Surface Wave Propagation

A ground wave travels along the surface of the earth. These waves are vertically polarized. So, vertical antennas are useful for these waves. If a horizontally polarized wave is propagated as a ground wave, due to the conductivity of the earth, the electric field of the wave gets short-circuited. As the ground wave travels away from the transmitting antenna it gets attenuated. To minimize this loss the transmission path must be over the ground with high conductivity. With respect to this condition, sea water should be the best conductor but it was observed that large storage of water in ponds, sandy or rocky Soil shows maximum losses. Hence, high power low-frequency transmitters, using ground wave propagations, are preferably located on ocean fronts. As ground losses increase rapidly with frequency, this propagation is used practically for signals up to frequency 2 MHz only.

Sky Wave Propagation

Every long radio Communication of medium and high frequencies are conducted using skywave propagation. In this mode reflection of EM waves from the ionized region in the upper part of the Atmosphere of the earth is used for transmission of waves to longer distances. This part of the atmosphere is called ionosphere which is at about 70-400 km height. Ionosphere reflects back the EM waves if the frequency is between 2 to 30 MHz’s. Hence, this mode of propagation is also called as Short wave propagation. Using sky wave propagation point to point communication over long distances is possible. With the multiple reflections of sky waves, global communication over extremely long distances is possible.

Space Wave Propagation

When we are dealing with EM waves of frequency between 30 MHz to 300 MHz, then space wave propagation is useful. Here properties of Troposphere are used for transmission. When operating in space wave propagation mode, the wave reaches the receiving antenna directly from the transmitter or after reflection from troposphere which is present at about 16km above the earth surface. Hence space wave mode consists of two components .i.e. direct wave and indirect wave.

Short wave broadcasting usually takes place in the frequency range of 1.7 – 30 MHz. As we have seen above the frequencies in this range are propagated through Skywave propagation mode. Depending on the frequency or wavelength the Electromagnetic Waves produce different affected in various materials and devices. Hence, the different parts of the electromagnetic spectrum are utilized for various applications.

Audible and Inaudible sound

Whenever an object vibrates ,sound is produced. When a simple pendulum vibrates, a sound is produced. But the sound produced by a vibrating simple pendulum is not heard by us. This is because the frequency of vibration of a simple pendulum is very low. It may be 2 or 3 hertz only.And our ears cannot hear sounds of such low frequencies. It is an inaudible sound which cannot be heard by us. An object must vibrate at the rate of at least 20 times per second to be able to produce audible sound.

The sounds having too low frequencies which cannot be heard by human ear are called infrasonic sounds. Rhinoceros can produce infrasonic sounds having frequency less than 20 hertz. They can also hear infrasonic sounds.

The human ear can hear sounds which have frequencies between 20 hertz and 20,000 hertz. The lower limit of frequency of human hearing is 20 Hertz and upper limit of human hearing is 20000 Hz. The sounds having too high frequency which cannot be heard by human ear are called ultrasonic sounds. The sounds of frequency greater than 20,000 hertz are called ultrasonic. The ultrasonic sounds cannot be heard by human beings.

The human beings can neither produce ultrasonic sound nor can they hear ultrasonic sounds.But there are some animal which can produce ultrasonic sounds as well as hear ultrasonic sound.

Noise and Music

The distinction between music and noise is mathematical form. Music is ordered sound. Noise is disordered sound. Music and noise are both mixtures of sound waves of different frequencies. The component frequencies of music are discrete (separable) and rational (their ratios form simple FRACTIONS) with a discernible dominant frequency. The component frequencies of noise are continuous (every frequency will be present over some range) and random (described by a Probability distribution) with no discernible dominant frequency.

A medium of propagation is a substance through which waves can travel. The most common types of waves are electromagnetic waves, such as Light and radio waves, and mechanical waves, such as sound waves.

The properties of a medium of propagation can affect the speed, direction, and attenuation of waves. For example, light travels faster in air than in water, and sound waves travel faster in solids than in liquids.

The following are some of the most common types of media of propagation:

Air: Air is a good medium for the propagation of electromagnetic waves, such as light and radio waves. It is also a good medium for the propagation of sound waves.
Aqueous solution: Aqueous solutions are solutions that contain water as the solvent. They are good media for the propagation of electromagnetic waves, such as light and radio waves. They are also good media for the propagation of sound waves.
Biological medium: Biological media are materials that are found in living organisms. They are good media for the propagation of electromagnetic waves, such as light and radio waves. They are also good media for the propagation of sound waves.
Dielectric: A dielectric is a material that does not conduct electricity. It is a good medium for the propagation of electromagnetic waves, such as light and radio waves.
Free space: Free space is the region of space that is not occupied by any matter. It is a good medium for the propagation of electromagnetic waves, such as light and radio waves.
Ground: The ground is the surface of the Earth. It is a good medium for the propagation of electromagnetic waves, such as radio waves.
Liquid: A liquid is a state of matter that is characterized by a lack of definite shape and a definite volume. It is a good medium for the propagation of sound waves.
Magnetic medium: A magnetic medium is a material that is capable of being magnetized. It is a good medium for the propagation of electromagnetic waves, such as radio waves.
Metal: A metal is a material that is characterized by its high electrical conductivity and its ability to be shaped by hammering or rolling. It is a good medium for the propagation of electromagnetic waves, such as radio waves.
Optical fiber: An optical fiber is a thin, flexible strand of glass or plastic that is used to transmit light. It is a good medium for the propagation of light waves.
Plasma: A plasma is a state of matter that is composed of charged particles, such as electrons and ions. It is a good medium for the propagation of electromagnetic waves, such as radio waves.
Solid: A solid is a state of matter that is characterized by its definite shape and its definite volume. It is a good medium for the propagation of sound waves.
Vacuum: A vacuum is a region of space that is devoid of matter. It is a good medium for the propagation of electromagnetic waves, such as light and radio waves.

The choice of medium of propagation depends on the type of wave that is being propagated and the desired characteristics of the propagation. For example, if you are trying to propagate light waves, you would choose a medium that has a high refractive index, such as glass or water. If you are trying to propagate sound waves, you would choose a medium that has a high density, such as metal or concrete.

What is a medium of propagation?

A medium of propagation is a material through which a wave can travel. The most common mediums are air, water, and solids.

What are the different types of waves?

There are many different types of waves, but some of the most common include:

Mechanical waves: These waves require a medium to travel through, such as sound waves and water waves.
Electromagnetic waves: These waves do not require a medium to travel through, such as light waves and radio waves.
Quantum waves: These waves are associated with subatomic particles, such as electrons and photons.

What is the speed of a wave?

The speed of a wave is the distance it travels in a given amount of time. The speed of a wave depends on the medium through which it is traveling and its wavelength.

What is the wavelength of a wave?

The wavelength of a wave is the distance between two consecutive crests or troughs of the wave. The wavelength of a wave is inversely proportional to its frequency.

What is the frequency of a wave?

The frequency of a wave is the number of waves that pass a given point in a given amount of time. The frequency of a wave is proportional to its speed.

What is the amplitude of a wave?

The amplitude of a wave is the maximum displacement of the wave from its equilibrium position. The amplitude of a wave determines its intensity.

What is the intensity of a wave?

The intensity of a wave is the amount of energy it carries per unit area. The intensity of a wave is proportional to the square of its amplitude.

What is the Doppler effect?

The Doppler effect is the change in the frequency of a wave as the source of the wave or the observer moves relative to each other. The Doppler effect is observed in all types of waves, including sound waves, light waves, and water waves.

What is the principle of superposition?

The principle of superposition states that when two or more waves meet, the resulting wave is the sum of the individual waves. This principle is important in understanding how waves interact with each other.

What is interference?

Interference is the phenomenon that occurs when two or more waves meet and their amplitudes add together or subtract from each other. Interference can be constructive or destructive. Constructive interference occurs when the waves are in phase, and the resulting wave has a larger amplitude than the individual waves. Destructive interference occurs when the waves are out of phase, and the resulting wave has a smaller amplitude than the individual waves.

What is diffraction?

Diffraction is the bending of waves as they pass through a narrow opening or around an obstacle. Diffraction is caused by the wave nature of light.

What is refraction?

Refraction is the bending of light as it passes from one medium to another. Refraction is caused by the difference in the speed of light in the two media.

What is reflection?

Reflection is the bouncing of light off a surface. Reflection can be either regular or diffuse. Regular reflection occurs when light bounces off a smooth surface, such as a mirror. Diffuse reflection occurs when light bounces off a rough surface, such as a wall.

What is absorption?

Absorption is the process by which a material takes in energy from a wave. Absorption can occur in any type of wave, including sound waves, light waves, and water waves.

What is scattering?

Scattering is the process by which a wave is redirected in many different directions. Scattering can occur in any type of wave, including sound waves, light waves, and water waves.

What is polarization?

Polarization is the property of a wave that describes the orientation of its electric field. A wave is said to be polarized if its electric field is always aligned in the same direction.

What is the difference between transverse waves and longitudinal waves?

Transverse waves are waves in which the particles of the medium move perpendicular to the direction of the wave. Longitudinal waves are waves in which the particles of the medium move parallel to the direction of the wave.

What is the difference between mechanical waves and electromagnetic waves?

Mechanical waves are waves that require a medium to travel through. Electromagnetic waves are waves that do not require a medium to travel through.

What is the difference between scalar waves and vector waves?

Scalar waves are waves that have only a magnitude. Vector waves are waves that have both a magnitude and a direction.

What is the difference between a standing wave and a traveling wave?

A standing wave is a wave that does not

Which of the following is not a type of Electromagnetic Wave?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following has the longest wavelength?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following has the highest frequency?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following is used in radar?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following is used in microwave ovens?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following is used in night vision goggles?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following is used in X-ray machines?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following is used in cancer treatment?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following is used in communication satellites?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays
Which of the following is used in WiFi?
(A) Radio waves
(B) Microwaves
(C) Infrared waves
(D) Visible light
(E) Gamma rays