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SCIENCE
Quarter II – Week 3
Practical Applications
of the Different Low Frequency
Electromagnetic Waves

CONTEXTUALIZED LEARNING ACTIVITY SHEETS

SCHOOLS DIVISION OF PUERTO PRINCESA CITY
Name: Grade & Section:

Lesson 1
Practical Applications of the
Different Low Frequency EM Waves
MELC: Cite examples of practical applications of the different regions of EM waves, such as
the use of radio waves in telecommunications. (S10FE-IIc-d-48)
Objectives:
1. Identify the different low frequency EM waves
2. Describe some practical applications of the different low frequency EM waves
3. Relate the importance of the different low frequency EM waves

Let’s Explore and Discover

In today’s technology-driven world, communication is
power. The society has become increasingly dependent on Did you know that…
communication networks. Hence, engineers and scientists
continue to search for more reliable and efficient Low frequency EM Waves
communication systems. consist of the following:
 Radio waves
Wireless communication has become possible across  Microwaves
and beyond the world through the transmission and  Infrared rays
reception of the radio waves, one of the regions of  Visible light
electromagnetic waves.
Electromagnetic waves have a vast range of practical everyday applications that
include the use of communication by cell phone and radio broadcasting, WiFi, cooking,
vision, medical imaging, and many more.
Are you ready to explore more about the different practical applications of the
different low frequency electromagnetic waves?

PRACTICAL APPLICATIONS OF THE DIFFERENT LOW FREQUENCY EM WAVES

Radio Communication
Radio waves can travel over long distances that is why they
are often used for communication. Aside from transmitting sound
and picture information from radio stations, radio waves are used
in airports, by safety officers in different establishments, and by
military officials to relay information. Even astronauts use radio
waves while they are in outer space to communicate with one another
because radio waves can also be transmitted through empty space.

Radio waves are produced by making electrons vibrate in an antenna. They have a
very wide range of wavelengths, and it is divided into smaller regions of wavebands. Each
waveband is allocated by law to a specific radio service.

Medium and high frequency waves are used for broadcasting by local radio
stations. In a radio station, sound is converted by a microphone into patterns of electric
current variations called audio-frequency (AF) signals. High frequency radio waves called
radio-frequency (RF) carriers can be modulated to match the electronic signal.

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 In amplitude modulation (AM), the amplitude of the
radio waves (RF carrier) changes to match that of the audio- Other Applications of
frequency (AF) signal. This is used in standard broadcasting Radiowaves
because it can be sent over long distances. Very high
frequency waves provide a higher quality broadcasting  Magnetic Resonance
Imaging (MRI)
including stereo sound. In this process, instead of the
 Tracking satellites
amplitude of the RF carrier, it is the frequency of the waves  Military surveillance
that changes to match that of the signal. This is called  Air traffic control
frequency modulation (FM).  Wifi
 Bluetooth
Low frequency waves are suitable for great distance.  Global Positioning
But the curvature of the earth limits the range to 80 km. To System (GPS)
extend the range, a repeater is used to receive the signal and  Radio frequency
identification (RFID)
to re-transmit it to the receiving station. High frequency
waves can be reflected by the ionosphere. This enables the
waves to be transmitted over great distances.

MICROWAVES

Satellite Communication
Microwaves can penetrate the atmosphere of the earth that is why they are used for
satellite communications. Microwave signals are transmitted by an antenna to a satellite
which amplifies and re-transmits the signal to an antenna in other parts of the world. This
is how we communicate with the rest of the world.
Most communication satellites are used to send and receive radio signals for
telephone services while the rest are for television broadcasting, scientific research, and
weather forecast.

RADAR
An acronym of Radio Detection and Ranging. It consists an antenna, transmitter,
and a receiver. The antenna whirls around to scan the surrounding area. The transmitter
sends out a narrow beam of microwaves in short pulses. A distant object reflects some of
the signal back to the receiver. The direction of the signal received gives the direction of the
object. The distance of the object can be calculated from the time lag between the
transmitted pulse and the reflected pulse.

Terrestrial Communication
Microwaves are used to transmit television news coverage from mobile
broadcast vehicles back to the station. The news crew can also set up a small antenna to
send signals to a communication satellite. This is how news are broadcasted and watched
live around the world.
A cell phone is a radio transmitter and
receiver that uses microwaves. Cellular phone is a
very sophisticated radio. It is today’s answer to the
emerging demand for mobile communication.
Cellular phones depend on overlapping network of
cells or areas of land several kilometers in diameter.
Each cell has its tower that receives and sends
microwaves signals.

Other Applications of Microwaves

 Microwave oven
 Remote sensing for disaster
 Weather forecasting
 Microwave Tomography

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 INFRARED (The Invisible Heat)
Infrared radiation lies beyond the red end of the visible
light. We do not see these rays but we feel it as heat.
People, objects, and animals give off infrared radiation
proportional to their temperature. The difference in color
determine the differences in temperature. For examples
shades of blue and green indicate regions of colder
temperature; and red and yellow indicate warmer
temperature.
(Image Source: Pixinoo. Simulation of body
temperature check by thermoscan or infrared
Some useful applications of Infrared Radiation:
thermal camera for against epidemic flu
covid19 or corona virus. Free Royalty.
 Infrared scanners are used to show the temperature
https://www.dreamstime.com/simulation-
variation of the body. This can be used for medical
body-temperature-check-thermoscan-infrared-
thermal-camera-against-epidemic-flu-covid-
diagnosis.
corona-virus-image179024205)
 Infrared remote controls used in TVs, recorders, and other
electronic appliances.
 Infrared camera has transmitter that sends out infrared pulses used in surveillance,
road safety, firefighting, search and rescue, and gas leak detection.
 Infrared lamps are used to keep chicken and duck eggs warm so that they can hatch.
 Infrared is used in night-vision cameras.
Infrared is also used in the following devices:
 Car locking system  Headphones  Incubator
 Computers (mouse, keyboard, printer)  Navigation system  Cooking
 Emergency response system  Signages

VISIBLE LIGHT (Windows to the Universe)

=It is the only EM wave perceived by the human
eye. If not because of the visible light, we will not be
able to see the beauty of our surrounding.

Our eyes are sensitive to electromagnetic waves

of wavelengths that range from 4x10-7 m to 7x10-7 m.
This is the range of wavelengths of white light. When
white light passes through a prism, it is separated
into its constituent colors: the red, orange, yellow, (Image Source: Unknown Author, license
green, blue, indigo, and violet. These colors do not from https://www.flickr.com/photos/12
distinctly separate but they continuously change from 1935927@N06/13580411493?muraadmi
red to violet. Red color has the longest wavelength npreview&muraadminpreview&mobilefor
mat=false)
from among these colors and violet has the shortest.
Applications of Visible Light Some Important Applications of Laser
Field of
Functions
 This is essential for photosynthesis. Application
Photosynthesis is the process by which Defense  Marking targets
green plant makes food.  Measuring range and speed
 Traffic lights  Being used as secretive
illuminators.
 Commercial displays
Industrial &  Cutting, drilling, cladding, and
 Optical fibers Commercial welding materials
 Car headlights and tail lights  Laser printers
 Every device that has viewable screen  Barcode scanners
(TV, liquid crystal display, touch-pad Medicine  Correcting vision
devices)  Cosmetic treatment
 LASER (Light amplification by  Bloodless surgery
stimulated emission of radiation). Laser Science &  Measuring pollutant gases
Technology  Detecting earthquakes &
is a device that emits light through a
underwater nuclear blast
process called optical amplification.  Producing 3D pictures in space
(Source: Herma D. Acosta, et al., Science Grade 10 Learner’s Material, First Edition, Pasig City: DepEd – BLR 2017. pages 150-160)