ILOILO NATIONAL HIGH SCHOOL
Luna Street, La Paz, Iloilo City
(for INHS classroom use only) Science 10
Quarter 2 - Week 1
At the end of the session, I would be able to:
S10FE-11a-b-47 MELC: Compare the relative wavelengths of different forms of
electromagnetic waves.
Concepts:
Electromagnetic (EM) waves or electromagnetic radiations are
produced by accelerating charges. EM Waves are transverse waves. These waves
can travel in a vacuum and in a material medium.
James Clerk Maxwell formulated the Electromagnetic Wave Theory
which says that an oscillating electric current should be capable of radiating energy
in the form of electromagnetic waves.
The Electromagnetic (EM) Spectrum is the continuous range of
electromagnetic waves arrange in order of decreasing of wavelength and increasing
frequency. The different types EM waves are: RADIOWAVES, MICROWAVES,
INFRARED WAVES, VISIBLE LIGHT, ULTRAVIOLET RAYS, XRAYS, and GAMMA RAYS.
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Figure 1. Electromagnetic Spectrum
https://sites.google.com/site/modernatomicehs/electromagnetic-radiation
Note: Unit of wavelength is m(meter) and frequency is Hz (hertz)
As shown in the diagram above Radio waves has the longest wavelength and
has the lowest frequency while Gamma Ray has the shortest wavelength and has
the highest frequency.
The Regions of the EM Spectrum
Radio wave – the longest of all electromagnetic waves with wavelengths
ranging from 10-1 m to 104m and has the lowest frequencies ranging from 30kHz
(kilohertz = 103 hertz) to 3000MHz (megahertz= 106 hertz). The bands are divided
into specific bands for wireless communication.
Table 1. Radio Frequency bands
Type of frequency Frequency Range
Low frequency 30- 300 kHz
Medium frequency 300- 3000 kHz
High frequency 3 – 30 MHz
Very high frequency 30 - 300 MHz
Ultra high frequency 300 – 3000 MHz
Microwaves are considered as high frequency radio waves which lie in the
EM spectrum somewhere from 300MHz to 300 GHz, with wavelengths corresponding
to 10-3m to 10-1m.
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ILOILO NATIONAL HIGH SCHOOL
Luna Street, La Paz, Iloilo City
(for INHS classroom use only) Science 10
Infrared radiations (IR) have a low frequency than the red part of the
visible light. Their frequencies range from 3 x1011Hz – 4 x 1014Hz, with wavelengths
ranging from 7.5 x10-7 m to 10-3 m.
Visible light is the only EM radiation perceived by the human eye. It lies
between IR and UV with frequencies ranging from 4 x1014Hz – 8 x 1014Hz, with
wavelengths ranging from 4 x10-7 m to 8 x10-7m. White light is made up of a variety
of colors with an acronym ROYGBV: red, orange, yellow, green, blue and violet.
Table 2. Wavelengths of the visible light spectrum Figure 2. Frequency of visible light spectrum
Note: 1nm( 1 nanometer) = 10-9m
https://www.quora.com/What-is-the-wavelength-of-the-visible-light Science10_Q2_Mod1_DifferentFormsOfEMWaves_V4.pdf
Ultraviolet Radiation (UV) is the part of the electromagnetic spectrum
that consists of frequencies higher than visible light but lower than X-rays. It has
frequencies ranging from 8 x 10 14 Hz to 10 17Hz and with wavelengths ranging from
6 x 10-10 m to 4 x 10- 7m. There are three kinds of UV: UVA, UVB, and UVC. UVA
has a wavelength range of 315 nm to 400 nm; UVB, from 280 nm to 314 nm; and
UVC, from 279nm to 60 nm.
X- rays have frequencies ranging from 3 x1016Hz to 3 x 1019Hz and
wavelengths ranging from 10-12m to 10-8m. X-rays are classified as either hard or
soft X-rays.
Gamma rays are emitted by sun and stars and can be given off by
radioactive materials like Cobalt -60 and Cesium- 137 or by interstellar matter and
remnants of supernova. They have the shortest wavelength, ranging from 10 -14 m
to 10-10m and the highest frequency greater than 3 x 1019 Hz.
The energy of an EM wave also depends on its frequency, which means
waves with higher frequency have higher energy too. Gamma rays have highest
energy and highly penetrating.
All EM waves move at the same speed (c = 3 x 108 m/s) in a vacuum and
differ from one another in frequency and wavelength. All EM waves follow the
basic wave equation,
v= fλ ,
where v is equal to c , f is its frequency and λ is its wavelength.
The unit of λ is m (meter), f is Hz(hertz ) or 1/s and v is m/s.
Jc/mstp/megPage 2
ILOILO NATIONAL HIGH SCHOOL
Luna Street, La Paz, Iloilo City
(for INHS classroom use only) Science 10
Thus, EM waves with long wavelength have low frequency and those with short
wavelength have high frequency.
longer wavelength - low frequency
Short wavelength - high frequency
Illustrative Examples:
1. A certain radio station has frequency of 101.5 MHz. What is its wavelength?
Given: f= 101. 5 MHz = 1.015 x 108Hz =1.015 x 108/s Asked: λ
Solution:
λ=__c__ = 3 .0 x 108 m/s = 2.955665025 m = 2.956m
f 1.015 x 108 /s
2. The wavelength of the red part of visible light is 760nm while that of the blue part is
470nm. Which has a greater frequency?
Given: λ red light = 760 nm = 7.6 x10-7m λ blue light= 470 nm = 4.7 x 10-7m
Asked: f red light and f blue light
Solution:
f red=__c__ = 3 .0 x 108 m/s = 3.947 Hz or /s
λ 7.6 x 10-7 m
f blue=__c__ = 3 .0 x 108 m/s = 6.383 Hz or /s
λ 4.7 x 10-7 m
Blue light has short wavelength but has high frequency.
References:
1. Pavico , J. M. , et al (2015) . Exploring Life Through Science series: The New Grade 10 ( 1st
edition)Phoenix Publishing House, Inc. , Quezon City.
2. Department of Education, Republic of the Philippines (2015) . Science 10 Learning Material.
3. Electomagnetic Radiation. Retrieve on July 5, 2020 from
https://sites.google.com/site/modernatomicehs/electromagnetic-radiation
4. Yorrekka(2019). What is the color of visible light? Retrieved on December 15, 2020 from
https://www.quora.com/What-is-the-wavelength-of-the-visible-light
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ILOILO NATIONAL HIGH SCHOOL
Luna Street, La Paz, Iloilo City
(for INHS classroom use only) Science 10
[Please use short sized bond paper for your answers. Write your name ( Last Name, First Name,
Middle Initial) , grade, section and date. Use the same format until Week 7]. When you’re done
please answer the Quiz for Q2 Week 1.
ACTIVITY 1
Name: ____________________________Grade 10 -________ Date:______ Score:____
A. Review
I. Direction: For questions 8 – 15 refer to the table below. Answer the following
questions briefly.
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ILOILO NATIONAL HIGH SCHOOL
Luna Street, La Paz, Iloilo City
(for INHS classroom use only) Science 10
8. Which electromagnetic wave has the longest wavelength?_____________________
9. Which electromagnetic wave has the shortest wavelength?____________________
10. Observe what happens to the wavelength of the electromagnetic waves as they
progress (goes rightward from the figure, in figure 2 on page2). Does the wavelength
of the EM waves increase or decrease as we go from radio wave to gamma ray?
__________________________________________
11. Which among the EM waves has the highest frequency?______________________
12. Which among the EM waves has the lowest frequency?_______________________
13. The energy of an EM wave also depends on its frequency, which means waves with
higher frequency has higher energy too. Which among the EM waves has the highest
energy? _________________________________________________________
14. Which among the EM waves has the lowest energy?__________________________
15. What happens to the frequency of the electromagnetic waves as it progresses?
Does the frequency of the EM waves increase or decrease as we go from radio wave to
gamma ray?____________________________________________________________
II. Problem Solving:
1. Calculate the wavelengths of the following electromagnetic waves.
(Note: gigahertz= 109 hertz; kilohertz = 103 hertz)
a) Microwave in an oven with a frequency of 2.45 GHz.
b) Radio waves used by submarines with a frequency of 24 kHz
2. The wavelength of the green part of visible light is 570nm while that of the
orange part is 620nm. Which has a greater frequency?
(Note: nanometer= 10-9 m)
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