this is my first presentation

1. MD. ENAMUL HAQUE
ID: EEE1601007140
SonargaonUniversity
Department of Electrical Electronic and Engineering

2. Contents
•What is Light ?
•What is the wave of a mono
chromatic wave along a ray ?
•Visible And Invisible LIGHT
•Electromagnetic Spectrum
•Why LIGHT is important ?
•Where does LIGHT comes form ?
•Where else does LIGHT come
form ?
•Sorting LIGHT sources
•LIGHT : Introduction
•LIGHT Carrey lot of information
•Speed of LIGHT

3. Where does light come from?
Our major
light source:
the Sun

4. Where else does light come from?

5. • We see things every day, from the moment we get
up in the morning until we go to sleep at night.
• We look at everything around us using light.
• Without light, you wouldn't see anything at all.
• There are two types of light: natural light or
artificial light.

6. Sorting light sources
Natural vs. Man-made (artificial)

7. Are these light sources?
moon
water
mirror
These items are not light sources, instead they
are reflecting light from other sources.

8. Light: Introduction
Isaac NewtonRobert Hooke Christian Huygens
For centuries the nature of light was disputed. In the 17th
century, Isaac Newton proposed the “corpuscular theory”
stating that light is composed of particles. Other scientists,
like Robert Hooke and Christian Huygens, believed light to
be a wave. Today we know that light behaves as both a
wave and as a particle. Light undergoes interference and
diffraction, as all waves do, but whenever light is emitted, it
is always done so in discreet of packets called photons.
These photons carry momentum, but not mass.

9. Light Can Carry a Lot of Information
• Holograms and fiber optics are two methods of information transfer that use light.
• Light is a wave, kind of like a wave in the ocean
• These light waves carry energy. This energy can do many interesting things, like help grow a
plant, produce electric currents, or cause chemical reactions.
• Light carries a different amount of energy depending on its wavelength
• Fiber optics is a method of sending information as light through a cable. This light signal can be
changed to music, video and more!

11. • Light travels at 300,000,000 meters/second
• It takes 8 minutes for a light wave (or a photon) to travel
from the sun to the earth.
• We see the moon because it reflects the sun’s light
• It takes 1 second for light reflected off the moon to reach
the earth.
Speed of light

13. Review: What is light "made of?"
• Light consists of electric (and magnetic)
fields moving through space at the speed of
light
The waveform can be replaced
by a set of arrows
perpendicular to the ray whose
tips lie along the waveform

14. Review: What is the wave of a mono-chromatic
(single wavelength) wave along a ray?
Speed of light in empty space is c = 186,000 miles/sec
= 3 x 108 meters/sec
Ray
Waveform
Amplitude
(maximum height)
The intensity of the
light is proportional to
the amplitude squared.
Large amplitude
means bright light.
Low amplitude means
dim light
Wavelength

15. What is Rayleigh scattering?
(or why is the sky blue)
• The shorter the wavelength, the more
light is scattered
– blue is scattered more than red.
– this is why the sky is blue and
sunsets are red. (Fig. 13.1)
Think of white light
from sun as a mixture
of R, G and B
Blue is scattered the
most so sky looks
blue when we look
away from the sun
For same reason sun
looks yellow (red +
green)
More atmosphere
allows next shortest
wavelengths (green)
to scatter so sunset
looks red

16. LIGHT
Visible LIGHT
• We now know what we see is
part of the electromagnetic
spectrum. We know that the
light waves enter our eye, and
stimulate parts of it that cause a
electrical impulse to be sent to
the brain which creates this
visual image
Invisible LIGHT
• When we see Without part of
electromagnetic spectrum. Like
as Gamma Ray ; X Ray;
Ultraviolet ; Infrared and
Radio .

17. Electromagnetic Spectrum

18. LASERS
When Source Light comes in to
Prism
Laser stands for light amplification by stimulated emission of
radiation. A laser is a device that creates and amplifies a narrow,
intense beam of coherent, monochromatic (one wavelength) light.

19. THINK:
Why is light important?

20. Shadows
• Shadows are caused
by opaque objects
blocking the path of
light.
• Long shadows are
seen in early morning
and late afternoon.
• Shorter shadows are
seen at noon.

21. Reflections
• Reflect is when light
or an image
bounces back off
an object’s surface.
• Light can bounce
back off an opaque
object.
• An image can
bounce back off an
object, such as, a
mirror, pond or lake,
or shiny metal.

22. Rainbow
• A rainbow appears in the
sky when the sun shines
through droplets of water
in the air, creating a
spectrum of color.
• The white light is broken
up into many colors.

23. Color
• The light we see is know as visible or white light –
although it is not that simple.
• The light is not really white, the white we see is a
combination of all the colors of the rainbow.
• Remember R-O-Y G. B-I-V from art class.
• When all of these light waves are combined we see
white light.

24. Color Reflection
• So if we see something as WHITE, that means …
– It reflected back all the wavelengths of light to our
eyes
• If we see something as RED or BLUE
– It reflected only the RED or only the BLUE wavelengths
– The others were absorbed.
• And if we see something as black?
– It did not reflect back any of the light.