How LED Works - Unravel the Mysteries of How LEDs Work!
Summary
TLDRThis video script delves into the workings of LEDs, explaining how these light-emitting diodes produce various colors by manipulating the semiconductor material inside. It covers the fundamental principles behind diodes and LEDs, their energy efficiency compared to incandescent lights, and the different types and applications of LEDs, including multi-color and high-powered LEDs. The script also touches on the importance of resistors in protecting LEDs from excessive current and introduces the concept of PN junctions in semiconductors, which are key to the color of light emitted. Additionally, it discusses the role of data brokers and the use of Incogni for privacy protection.
Takeaways
- π LEDs, or light-emitting diodes, emit light when a voltage is applied across them due to the semiconductor material inside.
- π Shining light onto an LED can reverse the process, producing a small voltage, demonstrating the dual nature of LEDs as light and electricity converters.
- π The color of the light produced by an LED is determined by the semiconductor material used, with different materials emitting different wavelengths of light within the visible spectrum.
- π LEDs are more energy-efficient than incandescent lights because they do not require heat to produce light, reducing energy consumption and heat generation.
- π The polarity of an LED is crucial; it only illuminates when the anode is connected to the positive side and the cathode to the negative.
- π The flat edge on an LED casing typically indicates the cathode side, helping to identify the correct connection polarity.
- π‘ There are various types of LEDs, including through-hole, surface-mount devices (SMD), high-powered, and multi-color LEDs, each suited for different applications.
- π οΈ LEDs require a current-limiting resistor to prevent damage from excessive current, with the brightness controlled by varying the current or voltage.
- π Bi-directional and RGB LEDs can change colors or mix colors to produce a range of hues, including white light, by controlling the current to individual diodes within the unit.
- π¬ The semiconductor material in LEDs is made by combining elements like gallium and arsenic, with impurities added to create n-type and p-type layers, which determine the emitted light color.
- π The development of LED technology has led to the creation of energy-efficient lighting solutions, such as LED bulbs, which are now widely used.
Q & A
What is the basic principle behind the light emission of an LED?
-An LED emits light when a voltage is applied across it, causing electrons in the semiconductor material to recombine with holes, which releases energy in the form of photons.
How does an LED symbol differ from a standard diode symbol in engineering drawings?
-An LED symbol is similar to a diode symbol but includes arrows that indicate light emission, distinguishing it from a standard diode which does not emit light.
What is the range of wavelengths for visible light to human eyes?
-Visible light to human eyes has a wavelength range of approximately 400 to 700 nanometers.
Why do standard diodes become hot, unlike LEDs?
-Standard diodes become hot because they produce photons in the near-infrared range, which are absorbed by the casing and converted to heat. LEDs, on the other hand, produce very little heat due to their different semiconductor materials and photon emission range.
What is the typical wavelength of the infrared light emitted by an LED in a TV remote?
-The typical wavelength of the infrared light emitted by an LED in a TV remote is around 940 nanometers, which is outside the visible spectrum for humans.
What is the main reason LEDs are more energy efficient compared to traditional incandescent lights?
-LEDs are more energy efficient because they do not need to produce heat to emit light, unlike incandescent lights which generate a lot of heat through the collisions of electrons with atoms in the filament.
What does the flat edge on one side of a through-hole LED indicate?
-The flat edge on one side of a through-hole LED indicates the cathode side of the LED, helping to identify the correct polarity for connection.
What is the purpose of the yellow phosphorus layer over a blue LED in some light bulbs?
-The yellow phosphorus layer over a blue LED in some light bulbs is used to combine with the blue light to produce a white light, as the mixture of yellow and blue light appears white to the human eye.
How can the color of an LED be changed by altering its semiconductor material?
-The color of an LED can be changed by altering the semiconductor material used in its construction. Different materials and their mixtures produce different band gaps, resulting in photons of different wavelengths and thus different colors of light.
What is the role of a resistor in an LED circuit?
-A resistor in an LED circuit is used to limit the current flow and protect the LED from being destroyed by an excessive amount of current. It also helps to control the brightness of the LED by varying the current.
How can the brightness of an LED be controlled?
-The brightness of an LED can be controlled by varying the current supplied to it. This can be achieved by using a resistor to set the current in the circuit or by using an LED driver that provides a constant current.
Outlines
π Understanding LEDs and Their Applications
This paragraph delves into the functioning of Light Emitting Diodes (LEDs), explaining how they emit light when a voltage is applied across them due to the semiconductor material inside. It contrasts LEDs with standard diodes, highlighting the visible light emission of LEDs within the human-visible spectrum of 400 to 700 nanometers. The script also touches on the use of LEDs in various applications, such as TV remotes emitting infrared light, and the energy efficiency of LEDs compared to incandescent lights. The paragraph introduces different types of LEDs, including through-hole and surface mount devices (SMD), and discusses the significance of the flat edge on LEDs, which indicates the cathode side.
π‘ Exploring LED Colors, Polarity, and Circuitry
The second paragraph focuses on the different colors of light emitted by LEDs, which are determined by the semiconductor material rather than the color of the LED case. It explains the importance of connecting the anode and cathode correctly to illuminate the LED and provides tips for identifying the polarity of an LED when the leads are trimmed or not easily distinguishable. The paragraph also covers various types of LEDs, such as bi-color and RGB LEDs, which can produce a spectrum of colors by controlling the voltage and current to each LED. Additionally, it discusses the use of resistors to protect LEDs from high currents and the role of LED drivers in ensuring stable operation.
π The Inner Workings of LEDs and Semiconductors
This paragraph provides an in-depth look at the internal structure of LEDs, including the anode and cathode leads, the epoxy resin casing, and the semiconductor layers that produce light. It explains the concept of a PN junction and how it forms a barrier that prevents the flow of electrons until a sufficient voltage is applied. The script also discusses the process of creating semiconductors by adding impurities to silicon to form n-type and p-type layers, and how the energy levels and band gaps of these materials determine the color of light emitted by the LED. It further explains how different semiconductor materials, such as gallium arsenide and gallium phosphide, can be combined to produce a range of colors, including white light, which has led to the widespread use of LED bulbs.
π The Science Behind Semiconductors and Color Production
The final paragraph explores the atomic structure and energy levels that underpin semiconductor behavior, explaining how electrons move between the valence and conduction bands. It details how different semiconductor materials, such as silicon, gallium arsenide, and gallium phosphide, have varying band gaps that affect the wavelength and color of the emitted light. The paragraph concludes by illustrating how mixing different ratios of these materials can produce a wide range of colors, including the primary colors red, green, and blue, which can be combined to create any color, including white light. It also mentions the use of incogni for data privacy and encourages viewers to continue learning about electronics through provided links and social media channels.
Mindmap
Keywords
π‘LED
π‘Semiconductor
π‘Photon
π‘Wavelength
π‘PN Junction
π‘Diode
π‘Visible Spectrum
π‘Infrared Light
π‘SMD
π‘RGB LED
π‘Resistor
Highlights
LEDs produce light through a semiconductor material that emits energy as photons when voltage is applied.
LEDs and diodes operate on the principle of semiconductor materials, but LEDs emit visible light photons for humans.
The visible light spectrum for humans ranges from 400 to 700 nanometers, which produces different colors.
LEDs are used in various applications, including TV remotes that emit infrared light with a wavelength of around 940 nanometers.
Standard diodes produce near-infrared photons absorbed by the casing and converted to heat, unlike LEDs which are cooler.
Incandescent lights generate a lot of heat, while LEDs are more energy efficient as they don't need to produce heat to emit light.
Different types of LEDs include through-hole, SMD, high-powered, and bi-color LEDs for various applications.
LEDs with color lenses or transparent versions emit different colors based on the semiconductor material, not the case color.
LEDs illuminate when connected correctly with the anode to positive and cathode to negative, and polarity can be identified by the flat edge on the LED case.
Resistors are used to protect LEDs by reducing current and turning electrical energy into heat.
LEDs can be manually flashed or automated with circuits involving resistors, capacitors, and transistors.
RGB LEDs contain red, green, and blue LEDs that can be mixed to create any color, including white light.
LEDs require a specific voltage and current to operate without damage, which can be controlled with LED drivers.
LEDs are made of semiconductor materials with a PN junction that emits photons of specific wavelengths when powered.
Different semiconductor materials like gallium arsenide and gallium phosphide are used to produce a range of visible light colors in LEDs.
The color of the LED light is determined by the wavelength of the emitted photon, which depends on the semiconductor material used.
By mixing different semiconductor materials, any color of light, including white, can be produced in LEDs.
Transcripts
sponsored by incopy why does this led
produce a red light but this one
produces a blue line when we apply a
voltage across an LED it produces light
it all comes from a tiny piece of
semiconductor material inside which is
emitting energy as photons but if we
shine a light onto the LED then we are
firing photons back into it so the
process reverses and it will also
produce a small voltage
80ds look something like this they come
in different shapes colors and sizes for
different applications LED stands for
light emitting diode we use this symbol
in engineering drawings for LEDs notice
it looks very similar to a diode symbol
except it has these arrows that indicate
that light is being emitted LEDs and
diodes both work on the same principle
it's just a semiconductor material in
the middle of some electrical connectors
they both emit photons but only the LED
emits photons in the range visible to
humans and that's when the photon has a
wavelength of around 400 to 700
nanometers we've received different
colors depending on the wavelength of
the photon in this range
FM radio signal is also a photon wave
but it's around 3 meters
Wi-Fi signal is smaller at around six
centimeters and a medical x-ray is Tiny
at around
0.01 nanometers but we can't see any of
these because they are outside of our
visible spectrum have you ever noticed
there's an LED in your TV remote
this emits infrared light the photon has
a wavelength typically around
940 nanometers so humans can't see it
however you can see it on the camera of
your phone
inside the semiconductor we just have
electrons combining with holes and
releasing photons in the process we will
learn how it works in more detail later
on in this video now a standard diode
uses different materials in its
semiconductor layer which produce
photons in the near infrared range these
are absorbed by the casing and converted
to heat so dodes become hot but LEDs
produce very little heat unlike
traditional incandescent lights which
generate a lot of heat in this design
the electrons collide with atoms in the
filament and these collisions produce
heat the filament heats up so much it
produces visible light
LEDs don't need to produce heat to
produce light and so they are much more
energy efficient most of you will
recognize this type of LED the five
millimeter through hole type but have
you ever noticed one side has a flat
Edge
tell me what you think this is for in
the comment section and I'll give you
the answer later on in this video
through-hole LEDs are perfect for
learning electronics we can buy them in
bulk very cheaply and I'll leave a link
for you in the video description for
where you can buy them these can be
inserted into test boards or even
soldered into printed circuit boards we
can get smaller three millimeter
versions or even larger 10 millimeter
versions typically they are Dome shaped
but there are other shapes available
like this square one we also get SMD
type which stands for surface mount
device these are soldered to circuit
boards to allow compact designs these
versions are much smaller some like this
one are so small you would need a
microscope to solder them we usually
find SMD LEDs used in our light bulbs
this one is actually a blue LED it just
has a layer of yellow phosphorus over it
and that's because the yellow and blue
light combined makes a white light we
can also get these very high powered
LEDs which are basically just lots of
LEDs packed tightly together and are
often used for torches and also flood
lights
LEDs can produce such Bright Lights
though we can see them from a great
distance but wait who is that oh no it's
a data broker he's copying all our
online personal information and selling
it for a profit luckily our sponsor
incogni will find and remove your
information
we all know that when we interact with
apps and websites we give away
information like our location history
names and aliases logging credentials
social security number phone numbers
search history interests Etc these are
all collected by data Brokers to form an
extensive profile about you and then
sold for example banks credit and
investment companies might buy
information about your financial status
your background and your employment
insurance companies might buy
information about your health now you
can manually contact each data broker
yourself or you can use incogni to
automate and track the process for you
you can try it right now and the first
100 people to use my code engineering
mindset using the link below will get 60
percent off do check it out links down
below LEDs come in various different
color lenses but we can also get
transparent versions which emit
different color light bytes too the
cases are only colored to make it easy
for us to tell what color light will be
produced is actually just the material
inside the semiconductor layer that
produces the different colors of light
and not the color of the case we will
learn how that works later on in this
video LEDs only illuminate when we
connect the anode lead to the positive
and the cathode to the negative take a
blue LED and a 3 volt coin battery
notice it only illuminates when
connected a certain way it's easy to
identify the correct polarity because
the longest lead of the LED is the anode
but what if the LED leads have been
trimmed well don't worry because one
side of the LED's case has a flat Edge
and this indicates the cathode side
additionally inside we can notice that
there are two metal plates the larger
plate is the cathode with snd LEDs we
find a small dot on the top sometimes
this is used to indicate the anode other
times this is for the cathode so you'll
have to check the manufacturer's
datasheet or test it yourself in this
example the LED illuminates when the
positive is connected to the dot side on
the back we find a marking but this
again could mean either the anode or
cathode here we can see the LED
illuminates when connected like this
we can manually flash LEDs by using a
switch or we can use a simple circuit
like this resistor capacitor and
transistor circuit to automate this and
here is the schematic for that circuit
but these blinking LEDs will turn on and
off by themselves automatically at a
certain frequency there's also these
type which change color by themselves in
a fast or slow transition
inside is a tiny controller that sets
the frequency and here is the schematic
for that circuit then we have
bi-directional LEDs these can change
between two colors inside there are two
LEDs connected in opposite ways so when
current flows this way one LED turns on
and when current flows the other way the
other LED turns on only one LED can be
turned on at a time however we can get
these three pin bio color type we can
manually switch them between one color
the other color or both colors together
these have two LEDs inside but they
share a terminal
then we have four pin RGB LEDs these
have three separate LEDs inside a red a
green and a blue and these all share a
terminal we can't activate them
separately two at a time to mix the
colors or all three to make a white
light we can control the voltage and
current to each led to make any color we
wish and here is the schematic for that
circuit now if you look closely at your
monitor you can see the same thing is
happening here too lots of tiny
multi-color LEDs by the way I've left
links for these LEDs in the video
description down below but where have
you seen these LEDs used or where could
you use them let me know in the comment
section down below if we try to connect
this led to this nine volt battery it
will instantly be destroyed inside the
LED is a thin wire the battery will try
to push so many electrons through this
wire that it just breaks
so we use a resistor to reduce the
current of electrons and you can watch
my video on how resistors work to learn
more the resistor removes energy from
the circuit to protect the LED it is
literally turning the electrical energy
into heat to remove it the battery is
providing 9 volts the resistor removes
around 7 volts and the LED will remove
the remaining two volts
the resistor is setting the current for
the circuit we can vary the current to
control the brightness of the LED but
when we vary the voltage Supply the
current will also vary the
manufacturer's datasheet will tell us
the rated voltage and current this led
is rated for 20 milliamps but we can go
slightly above or below this and it will
work fine the lower we go the dimmer the
LED will shine but if we go too high the
LED will be destroyed that's why we find
LED drivers inside light bulbs and also
dedicated units powering strip lighting
this lamp runs off of 230 volts the
rectifier is changing the alternating
current into direct current and the
capacitor is smoothing this out this
chip is providing a constant current to
the LEDs so that they don't flicker this
USB light strip is incredibly simple the
USB port provides a 5 volt Rail and a
ground Rail between them is just a
resistor and an LED each set is
connected in parallel which means we can
cut this to almost any length the more
LEDs we remove the lower the current
will be when we look at an LED we notice
there are two metal leads which connect
to the main body the longest lead is the
anode and the shortest lead is the
cathode the body is molded from an epoxy
resin these are often colored just to
make it easier to tell what color the
LED light will be on the side of the
case is a flat Edge this indicates the
cathode side looking inside the LED case
we see that both the anode and the
cathode leads each have a metal plate at
the end and these are separated by small
Gap the plates stop the knees from
turning the larger plate also indicates
the cathode side on the cathode plate we
typically find a cone shape within the
cone we find a small p piece of
semiconductor material made from a layer
of n-type material with a layer of
p-type material on top of this this
forms a p n Junction
a thin wire then runs between the ano
terminal and the p-type material to
complete the circuit when the LED is
powered photons are emitted from the PN
Junction of the semiconductor which
produces the colored light the cone
shape helps reflect the light out of the
top of the LED case
the color of the light depends on the
wavelength of the photon being emitted
from the semiconductor and that depends
on the material being used electricity
is the flow of electrons electrons flow
easily through conductors like copper
but they can't flow very easily through
insulators like rubber the n-type layer
has lots of free electrons and the
p-type layer is missing some electrons
but it has lots of holes that electrons
can go and sit in
electrons are negatively charged so the
letter N just lets us know which side
has a negative charge as electrons are
negative we consider the holes to be
positive and so we use the letter P to
make the semiconductor for a normal
diode we just use silicon this has four
electrons in its valence shell the atoms
will share these to become stable so
where do the electrons and holes come
from well we add some impurities like
phosphorus which has five electrons in
its valence shell these are shared with
the Silicon atoms but it will leave one
electron spare
this electron is free to move to other
atoms and so this is our n-type layer
for the p-type layer we add some
aluminum which only has three electrons
in the valence shell it doesn't have
enough to share with all of its
neighboring atoms so there will be a
hole where an electron can move too we
now have a layer with two many electrons
and also a layer with not enough
electrons this joins to form the PN
Junction
at this Junction we get a depletion
region
some of the electrons move across to
fill the holes and some of the holes
move across but this will create a
barrier with a slightly positively
charged region and a slightly negatively
charged region
this creates an electric field which
prevents more electrons moving across
when we connect a battery electrons will
flow and we call this a forward bias but
if the voltage is too small then we
can't break this barrier
with a normal diode we can see the
barrier is around 0.5 to 0.7 volts this
is the minimum voltage required for
current to flow but with a red LED it's
much higher around 1.7 volts the
manufacturer will provide a chart like
this which shows the forward current at
a certain forward voltage we can see
that it starts at around 1.7 volts
and we can see that at 2 volts we should
see around 20 milliamps of current
in this example that's exactly what we
see
now looking at a simple ball model of an
atom we have the nucleus at the center
which contains all the protons and
neutrons
then we have a number of orbital shells
where electrons can sit
each shell can hold a certain number of
electrons and an electron needs to have
a certain energy to be accepted into
that shell the further the distance of
the shell the more energy is required
the outermost shell is the valence band
just beyond this is the conduction band
electrons that reach this band can break
free from the atom in a conductor like
copper the conduction band is very close
so the electrons can easily move but in
an insulator like rubber the conduction
band is too far away so the electrons
can't escape but with a semiconductor
like Silicon the conduction band is just
a short distance away so it will act
like an insulator but when we apply a
voltage the electron in the valence
shell can break free
in the Silicon semiconductor like a
diode the electron is jumping from the
n-type conduction band to the p-type
valence band the valence band has less
energy than the conduction band so the
electron needs to lose some energy to be
accepted into this lower band it does
that by releasing a photon in Silicon it
needs to lose around 1.1 electron volts
to be accepted the energy of this photon
is equal to a wavelength of around
1127 nanometers and I'll show you how to
calculate that in just a moment that
means the Silicon diodes emit near
infrared light which humans can't see
so instead of silicon scientists mix
gallium and arsenic to form the
semiconductor
then they add some impurities to this to
form the n-type and the p-type layers
this semiconductor has a larger band gap
of around
1.424 electron volts and this produces
an 870 nanometer wavelength which is
better but still too high then they
tried gallium phosphide which has a band
gap of 2.26 electron volts and this
results in a wavelength of 548
nanometers which is perfect because the
human eye can see this and we see this
as green
so then scientists realize that by
blending the mixture of gallium arsenic
with gallium phosphide
they could achieve any color between
these two points
so if we mixed 60 gallium arsenic with
40 gallium phosphide we would get around
1.7 electron volts
we can convert that to a wavelength
using this formula so we drop these
numbers in to get this equation and this
gives us a wavelength of around 705
nanometers which produces a red light so
if we mixed 15 gallium arsenic with 85
gallium phosphide then this would give
us 2.13 electron volts which is a
wavelength of 580 nanometers and this
would give us yellow
so by mixing different materials
together to form the semiconductor this
will create different colored lights
once red green and blue could be
produced we can mix these colors to
produce any color we need including
white light and when white light was
possible LED bulbs became widely used
don't forget click the link down below
and the first 100 people to use my code
will get 60 percent off in cogni check
out one of the videos on screen now to
continue learning about Electronics
engineering and I'll catch you there for
the next lesson don't forget to follow
us on Facebook Twitter LinkedIn
Instagram Tick Tock and the
engineeringmindset.com
Browse More Related Video
Types of Diodes - The Learning Circuit
λΉλλ λλ§μ κ°μ± 무λλ± λ§λ€κΈ° - DDI λ°λ체 | λ°λ체 μμ©κ΅μ€ 4κ°
Basic Electricity - Resistance and Ohm's law
Circuit symbols (SP10a)
Komponen Penunjang Single Board Controller | Sistem Komputer | Informatika XII
Dasar Elektronika ; Dioda Sebagai Saklar
5.0 / 5 (0 votes)