Wave – is any disturbance propagating in a
medium or in a vacuum, carrying energy with it.
Things to consider
to have wave:
1. Source – a point
where the wave
started
2. Medium –
material where
the wave
travels
Classification of Wave according to the
Direction of Propagation
1. Longitudinal Wave – particles of the medium
vibrate parallel to the direction.
2. Transverse Wave – vibrate perpendicularly to
the direction.
Classification of wave according to the
medium of propagation
1. Mechanical
Wave – requires
a medium to
propagate.
2. Electromagnetic
Wave – Do not
require medium
to propagate.
ELECTROMAGNETIC WAVE
-A transverse wave that is composed of two
parts: the electric and magnetic field.
-these fields enable an electrically
charged/magnetic object to experience a force
without direct contact.
-The electric and magnetic field vibrate
perpendicularly to each other.
-An EM Wave travels at a speed of 3.0x10^8 m/s
EM Spectrum
- A variety of waves that are grouped according to their
wavelength and frequencies.
- They all travel at the same speed.
How waves are
described?
Characteristics of a Wave
Wave Equations
1. Frequency – represented by f
-it is the number of waves produced
in a given amount of time.
-its SI Unit is Hertz(Hz) 1 Hz=1/s or 1s^-1
𝑛 − 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑤𝑎𝑣𝑒𝑠
𝑓=
𝑇 − 𝑃𝑒𝑟𝑖𝑜𝑑(𝑡𝑖𝑚𝑒)
2. Period – represented by T.
-time for the source to produce one
complete wave
-its SI unit is seconds(sec).
𝑛 − 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑤𝑎𝑣𝑒𝑠
𝑇=
𝑓 − 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦
3. Amplitude – the maximum distance the
particles move away from their rest positions.
4. Wavelength – represented by λ
-distance between any two successive
points that are in place with each other.
-its SI unit is meters(m).
5. Speed of a Wave – represented by v
-distance the wave traveled per unit time.
𝑣 = 𝑓(𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦) 𝑥 λ(𝑤𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡)
𝜆 − 𝑤𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡
𝑣=
𝑇 − 𝑃𝑒𝑟𝑖𝑜𝑑
The speed of light in a certain material is
1.75𝑥108 𝑚 𝑠𝑒𝑐 . What is the wavelength of this light if
the frequency of the source is 7.5𝑥1014 𝐻𝑧?
Given: v = 1.75𝑥108 𝑚 𝑠𝑒𝑐 f = 7.5𝑥1014 𝐻𝑧
Solution : 𝑣 = 𝑓 𝑥 λ
𝑣
𝜆=
𝑓
1.75𝑥108 𝑚 𝑠𝑒𝑐
𝜆=
7.5𝑥1014 𝐻𝑧
𝜆 = 2.0𝑥10−7 𝑚
𝑣 = 𝑓(𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦) 𝑥 λ(𝑤𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡)
𝑣= 170.5
𝑠𝑒𝑐 𝑥 2𝑚
𝒗 = 𝟑𝟒𝟏 𝒎 𝒔𝒆𝒄
𝑣
𝜆=
𝑓
7𝑚
8.3𝑥10 𝑠𝑒𝑐
𝜆=
3.5𝑥10−6 𝐻𝑧
𝟐
𝝀 = 𝟐. 𝟗𝒙𝟏𝟎 𝒎
Electromagnetic waves
Produced by the movement of
electrically charged particles
Can travel in a “vacuum” (they do
NOT need a medium)
Travel at the speed of
light
Also known as EM waves
Radio waves
Longest wavelength EM waves
Uses:
TV broadcasting
AM and FM broadcast radio
Heart rate monitors
Cell phone communication
MRI (MAGNETIC RESONACE IMAGING)
Uses Short wave radio waves with a magnet to create an image
Microwaves
Wavelengths from 1 mm- 1 m
Uses:
Microwave ovens
Bluetooth headsets
Broadband Wireless Internet
Radar
GPS
Infrared Radiation
Wavelengths in between microwaves
and visible light
Uses:
Night vision goggles
Remote controls
Heat-seeking missiles
Visible light
Only type of EM wave able to
be detected by the human eye
Violet is the highest frequency
light
Red light is the lowest
frequency light
Ultraviolet
Shorter wavelengths than visible light
Uses:
Black lights
Security images on money
Harmful to living things
Used to sterilize medical equipment
Too much causes sun burn
Extremely high exposure can cause skin cancer
X-rays
Tiny wavelength, high
energy waves
Uses:
Medical imaging
Airport security
Moderate dose can damaging to cells
Gamma Rays
Smallest wavelengths, highest energy EM
waves
Uses
Sterilizes medical equipment
Cancer treatment to kill cancer cells
Kills nearly all living cells.
