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Applications of Waves

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Applications of Waves

Waves can seem endless and periodic but are far from boring! All travelling waves carry energy from one point to another; a property that has interested inventors and scientists alike for thousands of years. The energy from waves can be used to communicate long distances or even promote healing within the body. The applications of waves in everyday life are nearly endless.

The definition of waves

A wave is a disturbance in any material or medium that propagates (moves) from one place to another.

The particles in the medium vibrate with a specific predictable pattern which can be studied to find the characteristics of the wave. There are different types of waves, including sound waves, radio waves, microwaves, water waves, and light waves, among others. We will discuss the applications of some of these types of waves in this article.

Applications of wave motion

Water waves seem the most obvious and easily identifiable type of waves. The motion of the waves is periodic and sometimes tranquil but in the case of a tsunami, those waves can become destructive. One of the simplest applications of waves requires making use of the energy carried by water waves as they move. Tidal power is the power generated by the velocity of the flow of seawater. Tidal power stations are built in the ocean to capture tides as they move in and out. The kinetic energy of water can be used to generate electrical energy. The amount of energy currently generated by tidal power is not significant but it can be done, which in itself is remarkable. The image below is that of a typical tidal power station. This one is located in Russia.

Applications of Waves Tidal power station StudySmarterThis image is of the Kislaya Guba tidal power station in Russia where the kinetic energy of water waves is turned into electrical energy, Wikimedia Commons CC BY-SA 3.0

Applications of sound waves

Sound waves can be generated in gases, like air, but also liquids and solids. Sound waves are longitudinal waves, meaning the air particles vibrate in the same direction in which the wave is propagating.

Applications of sound waves: The Ear

The most common and probably most important use of sound waves is in everyday verbal communication. When we speak, the movement of the various parts of our mouth causes vibrations in the air surrounding it. These vibrations are carried through the air by disturbing neighbouring air molecules. This propagating chain of disturbances continues until the sound wave reaches its intended target, which is usually the ear of the person we are speaking to. Sound waves consist of areas in which air molecules are squashed closer together; these are called compressions. Areas in which the air molecules are further apart are called rarefactions. The figure below shows areas of compression and rarefaction in a typical sound wave.

Applications of Waves Sound wave StudySmarterA sound wave moving from source to ear. Dark areas have more vibrating air molecules (compressions) whereas lighter areas have fewer (rarefactions), Wikimedia Commons CC 1.0

The frequency limits of the human hearing range areto. Any sound with a frequency belowor greater thancannot be detected by a human. This frequency range is known as the audible spectrum.

The speed of any wave v is given in terms of its frequency f and wavelength λ by the formula v = f λ

Applications of sound waves: Sonar

Sound waves can be used for communication, music and other applications that rely on sound travelling through air. Sound can also travel through liquids and solids. Sound travels faster through water than it does through air, and also travels greater distances in water than in air. This fact is one of the factors that gave rise to the concept of sonar. Sonar is an acronym that stands for 'sound navigation and ranging'. It is the use of sound waves in water to detect underwater obstacles, such as sea mines, and objects that are hidden beneath the surface of the ocean, for example, submarines.

Sound waves travel at approximatelyin air at standard temperatures and pressures, but at a speed of approximatelythrough water.

Sound waves which travel through water undergo an important property of wave motion when they encounter an obstacle; reflection. A source of sound or ender emits a sound wave that travels outward, hits an object, is then reflected and returns toward the sender. A receiver is then used to detect the reflected wave (echo) and compare it to the profile of the original wave to ensure the reflection truly is the same wave. The distanceto the object can then be determined since the speed of the wave in water is known. The wave travels a total distance ofin the round trip to the object and back in a time. Since the speed of sound in wateris constant, the distancecan be found as follows by

Reflection is the property of wave motion that occurs when a wave moving in a medium is incident on a boundary or obstruction and bounces off that boundary before back into its original medium in a different direction.

The principle behind the operation of sonar can be viewed from the diagram below. The original wave strikes the obstruction, which is the object. It then reflects toward the sender and is eventually received.

Applications of Waves Diagram showing the principle behin the operation of a sonar StudySmarterThe principle behind the operation of sonar. A wave is emitted by a sender and received after being reflected by the object. The time taken for the wave to return indicates the distance of the object, Wikimedia Commons CC BY-SA 3.0

A stationary boat floating on the surface of a lake sends out a sound wave through the water directly below it. The reflection of the sound wave is receivedseconds later. Assuming the speed of sound in water to be, calculate the depthof the lake.

The speed of sound in water is constant. The sound wave travels straight down, reflects off the lake bed and returns to the boat inseconds. The depth of the lake can be calculated using the total travel time of the wave divided by two. Therefore the depth of the lakeis

Applications of sound waves: Ultrasound

If you have ever seen a scan of a baby in a pregnant woman, you would have seen an image that shows the features of the foetus. This is an example of the use of ultrasound waves in medicine. Ultrasound waves use a similar principle to that of sonar; reflection. A device called a transducer is used to generate and receive sound waves that have a frequency hundreds of times greater than the upper limit of human hearing. The sound waves are partially reflected at the boundaries of different tissues in the human body. Reflected waves are received by the transducer which transforms this into a digital signal that is viewed as the image. The various tissues and body structures reflect the waves in different directions and with different amplitudes. The result is an image of the structure of interest (tissue, organ, etc.) that is produced. The image below is an example of an image produced by ultrasound.

Applications of Waves Ultrasound image StudySmarterAn ultrasound image of the inferior vena cava in a human. An ultrasound pulse is sent into the body and the variations in the intensity of the reflected pulse are used to create this image, Wikimedia Commons CC 3.0

The ultrasound waves are only partially reflected because some of the waves may be refracted, scattered or absorbed by the boundary between tissues.

Ultrasound waves of lower frequencies can penetrate to a greater depth in tissue but the detail in the resultant image is lower. Higher frequency ultrasound waves cannot penetrate as deep but provide an image with a greater resolution. We can determine the depth of the boundary between tissues beneath the skin surface, using the equation that we did for sonar, i.e.,

whereis the speed of the ultrasound wave,is the total time taken for the wave to be emitted and received by the transducer andthe depth of the tissue boundary.

Applications of radio waves

Radio waves are the electromagnetic waves in the electromagnetic spectrum with the longest wavelengths of approximately. They can, hence, travel the longest distances of all electromagnetic waves. Due to this ability to travel long distances, radio waves are typically used for communication and detection. We will discuss two applications of radio waves, that are, mobile phones and radar. Radio waves contribute to background radiation and are generally considered safe, however, it is best practice to stay far from the source of radio waves. The international hazard symbol of harmful radio waves is shown in the figure below.

Applications of Waves Hazard symbol for radio waves StudySmarterThe image shows the hazard symbol for radio waves. It generally means that you are close to a source radio waves and should remain clear of the area, Public Domain Vectors

Applications of radio waves: Mobile phones

Not only do radio waves travel long distances, but they are also good at penetrating solid materials, such as walls. This makes the radio wave ideal for carrying cellular and telephone signals. Cellular phones have built-in receivers and transmitters. Transmitters work by converting audio signals into electromagnetic radio waves. The radio waves then travel long distances and are routed and relayed via cellular stations and towers until it reaches the phone of the recipient. The receiver then decodes the signal back into audio, which is played back to the recipient. Another advantage of radio waves in this application is that they travel at the speed of electromagnetic waves in free space, which is;million metres per second! This means that communication can happen almost instantaneously with very little delay. The figure below shows a picture of a typical cell tower.

Applications of Waves Cell phone tower StudySmarterThis image is of a typical cell tower that is used to relay radio waves from sender to receiver. The towers are usually tall to ensure that most of the waves are not absorbed by the ground, Pixabay

Applications of radio waves: Radar

Radar is an acronym that stands for radio detection and ranging. The principle behind Radar is quite similar to sonar, but electromagnetic waves are used rather than sound waves. Sound waves don't travel significantly fast enough in air to be useful in detecting obstacles, e.g., an incoming aircraft. We, therefore, turn to waves in the electromagnetic spectrum which can also undergo the wave motion property of reflection to detect objects that are in the sky. Radio waves are transmitted through the air via large antennas, reflect when they strike an obstacle and return via the same medium to the receiver. We can then use the time it takes for the radio wave to return to determine the distance to the object. The wave travels a total distance ofin the round trip to the object and back in a time. Since the speed of electromagnetic wavesin air is constant, the distancecan be found as follows by

The image below shows a picture of a radar antenna that can send out electromagnetic radio waves and receive the reflected waves as well. The size of the radar is proportional to the distance over which signals can be sent or received.

Applications of Waves Radar antenna StudySmarterAn image of a radar antenna that is capable of sending out a radio wave and receiving the reflected wave. The antenna is relatively large in size to ensure that signals can be sent and received over long distances, Pixabay

Application of light waves

Recall that light waves are electromagnetic waves, like radio waves, that lie in the visible region of the electromagnetic spectrum. Simply put, light is an electromagnetic wave that we can see. You may not think that there are many applications of light waves but that is probably because we have become accustomed to always having our surroundings illuminated. Spend a night without electricity and the importance of light suddenly becomes more apparent.

Applications of light waves: Flash photography

Have you ever noticed a professional photographer's bag? It is quite large in comparison to the size of the camera. One of the most important pieces of equipment, that can sometimes be larger than the camera itself, is the flash. A camera flash is a device that supplies a short, intense beam of light to illuminate the scene for a photograph to be taken. The white light produced is intense enough to brighten an image and allow for a clearer picture of higher quality to be taken. This is a simple but common example of the application of light waves. The figure below is that of a typical camera flash.

Applications of Waves A flash of a photo camera StudySmarterThis image shows a bright white flash that is generated by a modern digital camera. The flash is used to illuminate the scene for a photographer allowing for a clearer image to be taken, Wikimedia Commons

Applications of Waves - Key takeaways

  • Sound waves are created by vibrations of air molecules.
  • The frequency limits to human hearing areto.
  • Sound travels faster through water (∼) than it does through air ().
  • Sonar is ideal for underwater detection because of the high speed of sound through water and the fact that it can travel greater distances.
  • Sonar is based upon the wave property of reflection.
  • If the speed of sound in water, the distanceto an underwater object can be found by, whereis the total time taken for the wave to be emitted, reflected and received.

  • Ultrasound is based upon the wave property of reflection, similar to sonar.

  • In ultrasound imaging, a transducer is used to generate and receive the wave.

  • The frequency of ultrasound waves is much higher than the upper-frequency limit of human hearing.

  • Ultrasound waves are partially reflected by the boundary between tissues.

  • Ultrasound waves of lower frequencies can penetrate to a greater depth, but higher frequency ultrasound waves cannot penetrate as deep.

  • Radio waves are electromagnetic waves in the electromagnetic spectrum with large wavelengths.

  • Radio waves can travel long distances in air and penetrate solid materials.

  • Mobile phone signals are transmitted via radio waves, routed through the cellular stations, and received by other mobile phones.

  • Radar uses the wave property of reflection of electromagnetic waves.

  • Radar is used to detect objects and obstacles in air.

Frequently Asked Questions about Applications of Waves

Sound waves can be used for everyday verbal communication. Radio waves can be used for radio and mobile phone communication. 

Light sails can be used to propel spacecraft by using the pressure of light waves exerted on large solar sails.

Light waves can be used for illumination and lighting for photography. Certain wavelengths of laser light can also be used for medical diagnostic purposes.

Light waves are used in car headlamps to illuminate the road surface ahead of the car. Ships and boats may use stronger lamps to illuminate and navigate through the darkness. Radar technology is used in modern cars to detect obstacles outside the illumination of the headlights.

The speed of a wave in terms of its frequency and its wavelength λ is given by v = f × λ

Final Applications of Waves Quiz

Question

What is the approximate range of human hearing?

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Answer

20Hz to 20,000Hz

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Question

What are sounds with frequencies below the range of human hearing called?

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Answer

Infrasound

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Question

What are sounds with frequencies above the range of human hearing called?

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Answer

Ultrasound

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Question

Which of these is not a use of ultrasound?

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Answer

Detecting and measuring the size of Earthquakes

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Question

What is the approximate speed of sound in water?

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Answer

1500m/s

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Question

Which method is used to detect objects underwater and detect defects in industrial materials?

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Answer

Echo sounding

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Question

How is sound created?

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Answer

Vibration of particles

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Question

Why do we use ultrasound echo sounding when navigating the depths of the seas and not light?

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Answer

Light is heavily distorted when crossing the boundary between water and air. Furthermore, light has a low penetrating power below the water's surface.

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Question

What does SONAR stand for?

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Answer

Sound Navigation and Ranging

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Question

Name a reason why ultrasound tools are preferred by hygienists when cleaning teeth compared to manual scraping instruments?

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Answer

Any one of the following:


  • Patients report greater comfort during dental procedures.
  • The tips of the smaller ultrasound tools can more easily reach areas where manual tools would have more trouble.
  • Safety for those with weaker teeth, such as seniors. No scraping force is required when using ultrasound tools.

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Question

What can an ultrasound transducer do?

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Answer

Both transmit and receive ultrasound waves

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Question

Why do we use ultrasound scans and not X-ray scans when monitoring a foetus's development?

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Answer

X-rays possess very high energies, which could negatively impact the health of the unborn baby

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Question

If a piece of metal has a defect, will some of the reflected ultrasound waves return earlier or later than predicted?

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Answer

Earlier

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Question

Name one factor that can affect the speed of sound in water

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Answer

Any of the following:

  • Temperature
  • Salinity
  • Water Pressure

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Question

How are sound waves created?

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Answer

Vibration of air molecules

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Question

What are the frequency limits of human hearing?

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Answer

20 Hz to 20 kHz

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Question

Sound travels faster through air than it does through water.

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Answer

False

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Question

What is the speed of sound in air at standard temperature and pressure?

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Answer

330 ms-1

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Why is sonar ideal for detection underwater?

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Answer

Sound travels faster and greater distances through water than it does in air.

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Question

Upon which property of wave motion is sonar based?

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Answer

Reflection

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Question

Upon which property of wave motion is ultrasound based?

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Answer

Reflection

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Question

What is used to generate the sound waves for ultrasound imaging?

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Answer

Transducer

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Question

The frequency of ultrasound waves is much _____ than the upper-frequency limit of human hearing.

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Answer

higher

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Question

What happens to ultrasound waves at the boundary between tissues, that allows imaging to occur?

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Answer

They are partially reflected.

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Question

Ultrasound waves of lower frequencies can penetrate to _____ depth than waves of higher frequencies.


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Answer

a greater

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What type of waves are radio waves?

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Answer

Electromagnetic waves

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Radio waves can penetrate solid objects well.

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Answer

True

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Mobile phones can transmit and receive radio waves.

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Answer

True

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Radar is used to detect objects and obstacles in water.

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Answer

False

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Question

Would your next-door neighbour with an infrared receiver be able to eavesdrop on any infrared communications within your own home?

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Answer

No

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Question

Which things are essential for echolocation?

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Answer

A wave

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Question

Describe the process of echolocation.

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Answer

1. Make a sound
2. Wait until you hear its echo
3. Calculate the distance to the object (based on the speed of sound in the right medium and the time between making the sound and hearing the echo)

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Question

If the speed of sound is constant, why don't we always use the same value in the formulas for echolocation?

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Answer

Because - although it is constant within a specific medium - the speed of sound is different for every medium. We need to know through which medium the sound is travelling before we can fill in a value.

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Question

A bat screeched, and it hears an echo first in its left ear and then another in the right. On which side is the object that is closest to the bat?

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Answer

On its left.

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Question

Why do you need at least two ears to get information about the direction of an object using echolocation if (like bats)  you can't produce directed sound beams?

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Answer

You will need to know the direction of the echo, and this is only possible by measuring the timing difference of the echo's arrival between multiple ears.

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What information other than position can you gather about an object using echolocation?

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Answer

Velocity, size, and density.

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Why is echolocation useful underwater during the day?

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Answer

Light does not get transmitted well through water, so your sight is limited to a couple of meters. Sound waves travel much further, so you can map a much bigger chunk of your surroundings using echolocation.

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Question

Echolocation ALWAYS uses sound.

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Answer

True

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Define echolocation.

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Answer

Echolocation is the use of echoes, i.e. reflected sound, to locate objects.

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Question

Name one biological and one physical reason why echolocation sounds are mostly ultrasonic.

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Answer

1. Other animals (predators and prey) cannot hear where you are.
2. Higher frequency waves provide a higher resolution mapping.

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Question

Do you think a ship has only 1 or many microphones for the purpose of detecting echoes?

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Answer

Ships always have multiple microphones, so they can know the direction of the objects they detect. If you spot a dangerous underwater rock, you want to know where it is!

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Question

Why can't all animals echolocate?

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Answer

You need to produce your own (loud) sound in order to echolocate. This costs valuable energy compared to standard vision, which simply uses light waves that were reflected by objects and created by the Sun.

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Question

Sound waves will dampen as they propagate from their source. What does this mean?

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Answer

The sound will get quieter with distance

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Question

Which part of the electromagnetic spectrum has the largest wavelengths and lowest frequency?

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Answer

Radio Waves

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Question

Do we primarily use high-frequency or low-frequency waves in communications?

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Answer

Low-frequency

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Question

Which part of the electromagnetic spectrum below is NOT absorbed by the Earth's atmosphere?

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Answer

Microwaves

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Question

Name one reason why ultraviolet communications could be useful.

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Answer

  1. The high frequency of ultraviolet light would allow for a very high data transfer rate.
  2. Ultraviolet light is scattered by the Earth's atmosphere, so a UV signal could spread out as it travels and scatter around obstacles blocking line of sight. 

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Question

When a radio wave is absorbed by a conductor, what sort of current does it generate?

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Answer

Alternating current

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Question

Below a certain frequency, radio waves begin to bend over the horizon, allowing for a greater range of transmission. What frequency is this?

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Answer

3MHz

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Question

Why isn't skywave propagation used regularly today?

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Answer

Atmospheric conditions are unreliable.

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