Prelim Flashcards
● Branch of physics which involves the
behavior and properties of light, including
its interaction with matter and the
construction of instruments that use or
detect it
● Usually describes the behavior of visible,
ultraviolet, and infrared light
.
OPTICS
- Deals with the formation of images by light
rays; includes the study of the influence of
plane and spherical mirrors, plane and
spherical refractors, thin and thick lenses,
prisms, and optical system upon light
.
GEOMETRICAL OPTICS
- Deals with the physical character and
behavior of light and its interaction with
matter
PHYSICAL OPTICS
- Deals with the interaction of light with the
atomic entities of matter and methods of
quantum mechanics
QUANTUM OPTICS
Form of radiant energy that makes object
visible, makes vision possible
● Light energy from the sun travels through
space, reaches earth, and some of it turns
to heat energy and warms the earth’s air
● When light reaches an object, it is
absorbed, reflected, or passes through.
LIGHT
Properties of light
- Light travels in straight lines.
- Light travels very fast.
Speed of light = 186,000 mi/s (300,000
- Light emitted by luminous objects is
composed of a stream of corpuscles which
are tiny particles of matter that travel in
straight lines, at a finite speed, and have
different sizes corresponding to different
colors - Light traveling from air to water increases
speed, while light entering water will
decrease the speed - When corpuscles fall on the retina, they
produce an image of the object or
sensation of vision - Accounts for Reflection and Dispersion
Sir Isaac Newton in the late 17th century
Undulatory Theory
- Light is emitted in a series of waves that
spread out from a source in all directions
- These waves are not affected by gravity
- Introduced the concept of wavefronts and
the Huygens’ principle, which states that
every point on a wavefront is a source of
secondary spherical wavelets
- Disagreed with Newton and said that light
traveling from air to water will decrease
speed and vice versa
- Accounts for Diffraction and Refraction
Christiaan Huygens in 1678
- Performed a decisive experiment that
seemed to demand a wave interpretation,
turning the side of support to the wave
theory of light
Thomas Young
- Performed an experimental support for the
Wave Theory
Heinrich Hertz
- Published results of his experiments and
analysis, which required that light be a transverse wave
-Assumed that light waves in an ether were
necessarily longitudinal, light rays can not
pass around obstacles
Augustin Fresnel
- Light has its origin in ether waves set up by
electrical disturbances - “This velocity is so nearly that of light, that
it seems we have strong reason to conclude
that light itself (including radiant heat, and
other radiations if any) is an
electromagnetic disturbance in the form of
waves propagated through the
electromagnetic field according to
electromagnetic laws”
19th Century - From then on, light was viewed as a
particular region of the electromagnetic
spectrum of radiation - Light is an electromagnetic wave!
Electromagnetic Theory (Maxwell)
- Light waves travel as separate packets of
energy called quanta or photons - Merged the subjects of the Corpuscular,
Wave, and Electromagnetic Theories
together - introduced the concept of
quantization of energy, and Einstein
proposed that light consists of particles
called photons, which carry energy in
discrete packets or quanta. This theory
suggests that light exhibits both wave-like
and particle-like properties, leading to the
concept of wave-particle duality. - Proven to be the correct and most accurate theory.
Quantum Theory
Max Planck in 1900
Based on 3 Fundamental Laws:
○ The Law of Rectilinear Propagation
○ The Law of Reflection
○ The Law of Refraction
Substance:
Vacuum
Air
Ice
Water
Ethyl alcohol
Crown glass
Light flint glass
Dense flint glass
Zircon
Diamond
Polycarbonate
CR-39
PMMA
1.0000
1.000
1.31
1.333
1.36
1.523
1.58
1.67
1.923
2.417
1.58
1.49
1.49
● Light waves are three dimensional
● Light waves vibrate in all planes around a center line
Electromagnetic Radiation Waves
-a disturbance that travels in a
hypothetical medium called ether
WAVE
wave whose particles of
the medium vibrate at right angle to the
direction in which the wave travels.
Transverse wave
transverse waves in which
the direction of vibration is at right angles
to the direction of propagation.
Wave motion
path of single corpuscle of light from a
single point on a light source
RAY
collection of divergent, convergent,
or parallel rays
a. Divergent pencil: rays leaving a
point on a source that travel away
from each other and do not cross at
any point
b. Convergent pencil: rays that are
aimed toward a single point on an
image or object
c. Parallel pencil: rays emitted by a
source at an infinite position.
PENCIL
a collection of divergent,
convergent, or parallel pencils arising from
an extended source.
BEAM OF LIGHT
● The vergence of pencil at any particular
position is the reciprocal of the distance
from the position to the luminous point or
the focus
● The unit of vergence is the diopter—the
vergence of a pencil one meter from a
luminous point or focus
VERGENCE
● The vergence of pencil at any particular
position is the reciprocal of the distance
from the position to the luminous point or
the focus
● The unit of vergence is the diopter—the
vergence of a pencil one meter from a
luminous point or focus
VERGENCE
● A special source of light of only one pure
color (wavelength)
● Cannot be broken up into other colors
● Can be focused to a very small spot and can
shine for long distances without spreading
out very much (unlike flashlight)
● The spot contains a lot of energy—so much
that some lasers can cut through thick metal
(and smaller ones are used as scalpels in
LASER
SOURCES OF LIGHT
According to its nature
-natural sources-cannot be controlled by man( example: sun)
-Artificial sources- can be controlled by man (example bulb)
SOURCES OF LIGHT
ACCORDING TO SIZE
-POINT SOURCE -INFINITELY SMALL
-EXTENDED SOURCE- HAS MEASURABLE AREA CONSISTINV OF INFINITE NUMBER OF POINT SOURCE.
Light travels very fast.
-Speef of light = 186,000 miles per second
-300,000 kilometers per second
● type of energy that travels
through the air and space
● have long wavelengths, which
means they can travel long
distances and pass through
things like walls part of the
electromagnetic spectrum
● The modern term “radio wave”
replaced the original name
Hertzian Wave around 1912
RADIO WAVE
● predicted that there should be
light with even longer
wavelengths than infrared light
● Early discovery of radio wave
JAMES CLERK MAXWELL -1867
● demonstrated the existence of
the waves predicted by Maxwell
by producing radio waves in his
laboratory.
HEINRICH HERTZ- 1887
● number of wave cycles that pass
a point in one second, measured
in hertz (Hz)
FREQUENCY
● distance between two
consecutive peaks of the wave
WAVELENGTH
The radio wave spectrum spans from
low frequencies around 3 kHz (kilohertz)
to high frequencies up to 300 GHz
(Gigahertz), with varying wavelengths.
Low-frequency waves are ideal for
long-distance communication, like AM
radio, as they can travel further and
penetrate buildings. High Frequency
waves, used in Wi-Fi and mobile phones,
are better for short-range
communication and carry more data.
This spectrum supports a variety of
technologies, each suited to
specific need
SPECTRUM OF RADIO WAVE
2 TYPES OF RADIO WAVE SIGNAL
.
ANALOG SIGNAL
DIGITAL SIGNAL
● -It consists of a continuous signal
which is analogous to some other
quantity. For instance, the signal
voltage varies with the pressure
of the sound waves.
ANALOG SIGNAL
● It consists of a signal which only
consists of discrete values
DIGITAL SIGNAL
RADIO WAVES TRAVEL THROUGH
DIFFERENT MEDIUMS
Air,space and water
radio waves move easily, making it
the most common medium for
communication
AIR
where there’s no air, radio
waves can travel long distances without
much interference.
SPACE
absorbs radio waves more than
air does, so special low-frequency radio
waves are used for underwater
communication
Water
● These are long-range waves and
are reflected by the ionosphere.
HIGH FREQUENCY RADIO WAVES
30kHz to 3MHz
LOW MEDIUM FREQUENCY
1.7 to 30 MHz
SHORTWAVE FREQUENCY
88 to 108 MHz
HIGHEST FREQUENCY RADIO WAVE
30 to 300GHz
EXTREMELY HIGH FREQUENCY OR
MILLIMETERS WAVES
Radio wave propagation occurs
primarily in three modes.
-Ground wave propagation
● Sky wave propagation
● Line-of-sight propagation
Is a range of frequencies, wavelengths
and photon energies covering
Electromagnetic spectrum
A form of energy that can move through
the vacuum of space.
ELECTROMAGNETIC waves
DIFFERENT PHENOMENA
REFLECTION
REFRACTION
Diffraction
DIFFERENT PHENOMENA
REFLECTION
REFRACTION
Diffraction
is a key phenomenon in radio
wave transmission where radio
waves bounce off objects or
surfaces, depending on their
shape and material. This can
cause signal loss, distortion, or
multipath effects as the reflected
waves interfere with the original
signal.
REFLECTION
radio waves change direction
when they pass through media
with different refractive indices,
altering their speed and bending
towards or away from the
boundary between the media.
This affects the propagation path
and signal strength.
REFRACTION
When radio waves encounter
obstacles or openings
comparable in size to their
wavelength, they bend around
the obstacles and spread out. The
extent of diffraction depends on
the wavelength and the size of
the obstacle or opening, leading
to complex wave patterns.
DIFFRACTION
Electromagnetic waves are
shown by a
Sinusoidal Group
Electromagnetic waves is
Transverse nature
Are a type of electromagnetic radiation
with wavelengths ranging from one
millimeter to one meter, falling between
radio waves and infrared light on the
electromagnetic spectrum.
MICROWAVE
In general, refers to waves of electric
and magnetic fields that propagate
through space, carrying energy.
ELECTROMAGNETIC RADIATION
1864, theorized
electromagnetic radiation,
James clerk Maxwell
until experiments in
1886 that microwaves were confirmed.
HEINRICH HERTZ-
● An American physicist and
electrical engineer who invented
the magnetron, a vacuum tube
that generates high-frequency
electromagnetic waves, including
microwaves
ALBERT WALLACE HULL
an engineer at
Raytheon, accidentally discovered
that microwaves could heat food when
a chocolate bar melted in his pocket
during radar experiments. This led to
the invention of the microwave oven
1945 PERCY SPENCER
★ have shorter
wavelengths and higher
frequencies than radio waves
Microwaves
can penetrate
materials that are opaque to
visible light
Microwaves
Type of Radars in Microwaves
- Air Traffic Control
● Military Radar
Microwaves have radiatio
● is a type of electromagnetic
radiation that lies just beyond the
visible spectrum, with
wavelengths longer than visible
light but shorter than
microwaves.
● It is also referred to as heat or
thermal waves is a type of
electromagnetic wave. This is
because they have a heat
inducing property
INFRARED LIGHT
Infrared waves are
than visible light
LONGER
Infrared waves are
than radio waves
Shorter
is invisible to the
human eye.
Infrared light
● who discovered infrared
Freddrick willian Herschel 1880
has numerous uses
and is vital to many different sectors. It
has applications in data networking,
telecommunications, astronomy,
meteorology, and thermal imaging.
Since infrared radiation plays a role in
climate change, it is significant.
Infrared radiation are absorbed and
emitted by greenhouse gasses, raising
the earth’s surface and atmospheric
temperature. We call this the
greenhouse effect.
USES OF INFRARED RADIATION
Showed that the sun emits infrared light
by using a prism to refract light from
the sun and detected the infrared,
beyond the red part of the spectrum,
through an increase of the spectrum
recorded on a thermometer
COLORiFIC RAYS
Types of Infrared
Near-Infrared Radiation
Mid-infrafred Radiation
Far-infrared Radiation
Shortest infrared wavelength
(nearest the visible spectrum), with
wavelengths 0.78 to about 2.5
micrometers (a micrometer, or micron, is
10-6 meter)
Near - Infrared (NIR)
with wavelengths 2.5 to
about 50 micrometers
Mid - Infrared (MIR)
refers to a
specific range within the infrared
spectrum of electromagnetic radiation.
FAR INFRARED RADIATION (F.I.R)
Five categories in infrared light
● Near-infrared.
● Short-wavelength infrared.
● Mid-infrared.
● Long-wavelength infrared.
● Far-infrared.
has a wavelength
of 700 nm to 1,300 nm or 0.7 microns
to 1.3 micron
NEAR INFRARED
has a frequency
of 215 THz to 400 THz
NEAR INFRARED (NIR)
- has a wavelength
of 300 nm to 3,000 nm or 1.3 microns
-to 3 micron has a frequency of
20 THz to 215 THz
MID-INFRAFRED
-has a wavelength
of 3,000 nm to 1 mm or 3 microns to
1,000 microns
-has a frequency of
0.3 THz to 20 THz
FAR-INFRARED
-is the portion of the
electromagnetic spectrum that is
detectable by the human eye. It
consists of electromagnetic waves with
wavelengths ranging from
approximately 380 nanometers (nm) to
700 nm. Within this range, different
wavelengths correspond to different
colors that we perceive:
VISIBLE LIGHT
-those beyond the range of human
vision. Interestingly, the majority of
light in the universe is actually invisible
to our eyes. The visible light we can see,
which includes the colors of the rainbow,
forms just a tiny fraction of the entire
electromagnetic spectrum. Beyond this
visible range are other forms of light,
such as radio waves, microwaves,
ultraviolet rays, X-rays, and gamma
rays—all of which cannot be detected by
human sight. All forms of light, or
electromagnetic radiation, travel
through space at a speed of 186,000
miles per second.
The electromagnetic spectrum
encompasses all types of light, including
involves phenomena like
reflection, refraction, dispersion,
diffraction, and interference, which
describe how light interacts with
different materials and surfaces.
Visible light in optics
involves phenomena like
reflection, refraction, dispersion,
diffraction, and interference, which
describe how light interacts with
different materials and surfaces.
Visible light in optics
Characteristics of Visible Light:
-wavelength
-color
-energy
-speed
-shortest wavelength (400 nm),
VIOLET
longest wavelength (700 nm),
RED
Speed of visible light about:
299,792 km/s
-between 400 to 750 terahertz (THz
FREQUENCY OF VISIBLE LIGHT
-between 400 and 700 nanometers
Wavelength of visible light
In the 1660s, English physicist and
mathematician. He demonstrated that clear
white light was composed of seven
visible colors.in a room with closed
shutters, he works with a small opening
to isolate a single ray of sunlight. In the
stream of light, he places a glass prism:
Via refraction, the light breaks down
into a rainbow of colors: Red, orange,
yellow, green, blue, indigo, violet. By
scientifically establishing our visible
spectrum (the colors we see in a
rainbow), Newton laid the path for
others to experiment with color in a
scientific manner. His work led to
breakthroughs in optics, physics,
chemistry, perception, and the study of
color in nature.
ISAAC NEWTON
● type of
electromagnetic radiation with a
very short wavelength ranging
from 0.01 to 10 nanometers,
corresponding to frequencies in
the range 3 x 1019 Hz to 3x1016
Hz capable of penetrating
various materials.
● It is a very important diagnostic
tool for medical conditions like
bone fractures, pulmonary
tuberculosis, etc.
X-RAY
German physicist_______ is
typically credited for the discovery of
X-rays in 1895.
● He named it X-Radiations to
signify an unknown type of
radiation.
Wilhelm RONTGEN
World’s first x-ray Image
The first X-Ray image obtained was the?
hand of Wilhelm Rontgen’s wife, taken
on 22nd December, 1895.
● X-rays are situated between
ultraviolet light and gamma rays
in the electromagnetic spectrum.
● X-rays are a type of
electromagnetic radiation, which
means they share the same
fundamental nature as visible
light, radio waves, and gamma
rays. However, they differ in their
wavelength and frequency.
X-rays have much shorter
wavelengths
ELECTROMAGNETIC SPECTRUM
● X-rays are situated between
ultraviolet light and gamma rays
in the electromagnetic spectrum.
● X-rays are a type of
electromagnetic radiation, which
means they share the same
fundamental nature as visible
light, radio waves, and gamma
rays. However, they differ in their
wavelength and frequency.
X-rays have much shorter
wavelengths
ELECTROMAGNETIC SPECTRUM
-The most common method
of producing X-rays involves an X-ray
tube, a specialized device that
converts electrical energy into X-ray
radiation.
X-Ray tube
● X-rays are generated when
high-speed electrons collide with
a metal target (typically
tungsten) in an X-ray tube.
PRODUCTION
TYPES OF X-RAYS:
SOFT X-RAY
Hard X-ray
Lower energy, used for medical
imaging.
SOFT X-RAY
Higher energy, used for industrial
applications.
Hard x-ray
Electrons are accelerated and then
decelerated abruptly when they hit a
target, releasing energy as X-rays.
● X-Ray Generation
X-rays pass through the body and are
captured on film or digital detectors to
create an image
Imaging Process
Absorption
Scattering
Interaction with Matter
Denser materials (like
bones) absorb more X-rays, creating
contrast in images.
Absorption
: X-rays can scatter when
they interact with matter, which can
lead to image blurring.
Scattering
MEDICAL APPLICATIONS OF X-RAY
Radiography
Computed Tomography (CT)
Mammography
Fluoroscopy
medical doctor with specialized training to study medical conditions using human tissue, blood, pee and other body fluids
Pathologist
● Chest X-rays: Used to diagnose
lung conditions like pneumonia or
tuberculosis.
● Bone X-rays: Detect fractures
and other bone abnormalities.
RADIOGRAPHY
● Provides cross-sectional images
of the body for detailed
examination of organs and
tissues.
COMPUTED tomography
● Specialized X-ray technique for
early detection of breast cancer
Mammography:
● Real-time X-ray imaging used
during procedures like catheter
insertions and orthopedic
surgeries.
Fluoroscopy
- refers to the region of
the electromagnetic spectrum between
visible light and X-rays, with a
wavelength falling between 400 and 10
nanometers
ULTRAVIOLET LIGHT
● UV light was first discovered by
- 1801 when he discovered that
invisible light rays darkened
paper soaked in silver chloride
faster than visible light
Johann William Ritter
-are the most harmful and are
almost completely absorbed by
our atmosphere.
UV-C rays
Different Types of UV Light
UV- A LIGHT
UV- B LIGHT
UV-C LIGHT
● Commonly known as “Black
Light” Has the ability to cause
objects to emit fluorescence
● It has the longest wavelength,
and the least harmful 320-400
nm
UV -A LIGHT 320-400NM
● Causing sunburns with prolonged
exposure may increase the risk of
skin cancer.
● About 95% 0f all UV-B light is
absorbed by the ozone in Earth’s
atmosphere
UV-B LIGHT 290-320 NM
● Is extremely harmful and is
aljmost completely absorbed by
Earth’s atmosphere.
● Is commonly used as a
disinfectant in food, air and
water to kill microorganisms by
destroying their cells’ nucleic
acids.
UV-C LIGHT 100-290 Nm
-Electromagnetic radiation is a special
kind of energy that travels in waves
through space. It is like a wave of
energy that can move without
needing anything else to carry it,
even in empty space.
GAMMA RAYS
-Gamma rays have the shortest
wavelengths and highest frequencies
of all the radiation. They are produced
during nuclear reactions and can be
very harmful
GAMMA RADIATION
● A French chemist and physicist,
discovered gamma radiation in
1900, while studying radiation
emitted from radium
PAUL VILLARD
● Greater than 10¹⁸ Hertz (Hz) until
10²⁴ Hz
FREQUENCY
● Generally less than 10 picometers
(pm), which is 10¯¹⁰ Nanometer
(nm) until 10¯¹⁵ nm. - The short
wavelength corresponds to their
high energy
Wavelengths
-Gamma rays have the high
among all electromagnetic radiation,
typically exceeding 100 keV
(kilo-electron volts)
HIGH ENERGY
As pure energy, gamma rays have no
mass or electrical charge
No Mass or Charge:
-Like all electromagnetic waves, gamma
rays travel at the speed of light
(approximately 3 × 10⁸ meters per
second in a vacuum).
Speed of light
Vacuum
1.0000
Air
1.000
Ice-
Water-
Ethyl alcohol -
1.31
1.333
1.36
Crown glass
Light flint glass
Dense flint glass
1.523
1.58
1.67
Zircon
Diamond
Polycarbonate
CR-39
PMMA
1.923
2.417
1.58
1.49
1.49
States that in a homogeneous and
isotropic optical medium light travels
along a straight path.
| “Light travels in straight line as long as it is
not reflected, refracted or absorbed.”
LAW OF RECTILINEAR
PROPAGATION
is the bouncing back of light
REFLECTION
The law of reflection states that:
{ The incident ray, the reflected ray and
the normal all lie in the same plane
{ The angle of incidence = Angle of refraction
LAWS OF REFLECTION
TYPES OF REFLECTION
Specular reflection
Diffuse reflection
is the bending of light
- light is transmitted undergoing changes in directions and velocity
REFRACTION
Laws of refraction state that:
{ The incident ray refracted ray, and the
normal to the interface of two media at
the point of incidence all lie on the
same plane.
{ The ratio of the sine of the angle of
incidence to the sine of the angle of
refraction is constant. This is also known as Snell’s law of refraction.
LAW OF REFRACTION
transformation of light into some other form of
energy
- When a photon collides with an atom or
molecule, it can transfer its energy to the
particles, causing electronic transitions or
vibrations within the material. As a result, the
energy of the absorbed photon is transformed into internal energy of the material
ABSORPTION
Light Encounter
Absorption
| Transmission
| Reflection
decomposition of light into its constituent
elements by refraction through a medium whose surfaces are not parallel (prism)
DISPERSION
the spreading of waves around obstacles
- slight bending of light around corners
- decomposition of light into its constituent elements through a hard, sharp objects
Diffraction
the process of
restricting the
vibration directions
of the
electromagnetic
wave to only one
direction
- the most common
method of
polarization is the
use of a polaroid filter
POLARIZATION
TYPES OF POLARIZATION
Linear
| Circular
| Elliptical
TYPES OF POLARIZATION
Linear
| Circular
| Elliptical
A body in which modifications of light always takes place
MEDIUM
has the property of transmitting rays of light
through it and bodies situated beyond or behind
it can be distinctly seen
- Light passes freely through it with a minimum absorption and reflection
- Example: clear window pane
TRANSPARENT
lets light pass through it but not all and a light
shadow is present
- Allows some light to pass through it but the light
cannot be clearly seen through
Example: frosted glass
TRANSLUCENT
all of the rays of light incident on it are reflected
or absorbed, so that none traverses it
- If light is blocked by an object and a dark
shadow is cast
- Example: wood door
OPAQUE
