How Do LEDs Work and Where Are They Used?
LED is a light-emitting diode, which is a semiconductor source of light. It emits light only when current flows through it.
An LED can emit a variety of colours. So what happens here is, the electron-hole combination releases energy in the form of chunks called packets, and the colour of the LED is ascertained by the energy released by electrons while crossing the energy bandgap in a semiconductor. Below you can see the multi-coloured LEDs:
[Image will be uploaded soon]
We find various uses of LED, starting from cell phones to TVs. Now, we will understand the uses of LED, application of LED.
LED Symbol
Just like the symbol of a battery, we have two terminals in a diode or an LED. Below is the LED symbol with its two terminals:
[Image will be uploaded soon]
Before we state the main practical application of led, we will understand some LED examples:
LED Examples
There are various types of LEDs that we find in our daily life applications; these are:
Miniature LEDs
Bi and Tri-colour LED
Flash LED
High-power LEDs
Alphanumeric LED
Red Green Blue or RGB LEDs
[Image will be uploaded soon]
RGB LED
Lightning LEDs (The ones we use as a Diwali light).
What are the Uses of LED?
We find the application of LED in various fields starting from optical communication, alarm to security systems. Furthermore, we find the uses of LED in remote-controlled operations, robotics, and much more.
We use LEDs because of their long-lasting capabilities, low power requirement, fast switching capacity, and rapid response time.
Application of LED
The major uses of LED are in lightning objects and places. Its application is found everywhere, be it regarding the compact size, low energy consumption, extended lifetime, and flexibility in terms of use in various applications. The list of the uses of LED is as follows:
TV backlight
Dimming lights
Smartphone displays
Automobile industries
Aviation lightning
Horticulture glowlights
General lightning
Camera flashes
Lighted wallpaper
Medical devices
Now, we will understand what is the use of LED in detail:
What is the Use of LED?
1. TV Back-Lighting
The backlight of a TV is costumes with a lot of power. When we use LEDs, as a backlight, it offers efficient power usage. Similarly, the placements of the lights on an LED TV can differ which means light-emitting diodes can be placed either behind the screen or around its edges.
When we use an LED at the TV’s edges, we find the cost reduction choice.
Using LEDs just behind the display offers good contrast. Because of this reason, CFLs and LCDs have been replaced by LEDs in TV backlighting.
2. Smartphone Backlighting
The LED display is easily available in markets if your smartphone has lost its display. The application of LED helps in thinning the backlight design of our smartphones and also makes it at a low cost. However, the price of LED may vary as per the sizes of the display of your smartphone, also, the lower output voltage ensures a longer battery life.
3. Displays
In the present time, LED display boards are easily available and are used in places like storage signs, billboards, road signs, etc.
Signboards having multiple languages convey signals with the help of LEDs, the use of more LEDs is always beneficial in terms of less power consumption.
4. Automotive Headlamps
LED usage in the automotive industry is rising sharply. It’s because LEDs save energy and make visibility clearer.
Further, they come in use more often in the back and rear of an automobile and provide better accessibility.
Moreover, they can also enhance the pedestrian’s and driver’s safety because of enhanced visibility in rear views, especially during night journeys.
5. Dimming of Lights
We find the application of LEDs as dimming lights because they reduce energy consumption. We can also use the dimming feature in appliances that require global, and local dimming.
6. Optical Switching Applications
We find the use of an LED in burglar alarm systems, in power level indicators, and stereo amplifiers.
Advantages of LED TVs
Below are the advantages of LED in a tabular form:
LEDs have many other advantages over incandescent light sources, including the following:
Improved physical robustness, and
Smaller size
Do You Know?
Early LEDs were mostly used as indicator lamps, in place of small incandescent bulbs, and they had seven-segment displays. However, recent developments have introduced high-output, low-power consuming white light LEDs suitable for room and outdoor area lighting.
FAQs on Practical Uses of LED in Physics
1. What is a Light Emitting Diode (LED), and what is its basic working principle?
A Light Emitting Diode (LED) is a heavily doped p-n junction diode that emits light when it is forward-biased. Its working principle is based on electroluminescence. When a suitable forward voltage is applied, electrons from the n-side and holes from the p-side recombine at the junction. During this recombination process, energy is released in the form of photons (light). The colour of the emitted light depends on the energy band gap of the semiconductor material used.
2. What are some common practical uses of LEDs in everyday life and technology?
LEDs are used in a vast range of applications due to their high efficiency and long life. Some common examples include:
Lighting: Used in energy-efficient home and office lighting, streetlights, and decorative lights.
Displays: Found in digital clocks, traffic signals, television screens, and smartphone displays.
Automotive: Employed as headlights, taillights, brake lights, and interior cabin lighting in modern vehicles.
Indicators: Serve as small indicator lights on electronic devices like remote controls, chargers, and laptops to show power status.
Optical Communication: Used in fibre optic systems and remote controls for transmitting information via light pulses.
3. Why are LEDs often preferred over traditional incandescent bulbs? What are their key advantages?
LEDs are preferred over traditional incandescent bulbs due to several significant advantages that make them a superior technology. The primary reasons are:
Energy Efficiency: They convert a much higher percentage of electrical energy directly into light, consuming significantly less power for the same brightness.
Long Lifespan: LEDs have an operational life of tens of thousands of hours, which is far longer than that of incandescent bulbs.
Durability: As solid-state devices, they are highly resistant to shock, vibrations, and external impacts.
Fast Switching: They achieve full brightness almost instantaneously, a property crucial for communications and traffic signals.
Low Heat Emission: They radiate very little heat, which improves efficiency and makes them safer to operate.
4. How is an LED correctly used in a circuit, and why is a series resistor necessary?
To function correctly, an LED must be connected in forward bias, where the positive terminal of the power source connects to the anode (longer lead) and the negative terminal to the cathode (shorter lead). A current-limiting resistor must always be placed in series with the LED. This is critical because an LED has very low internal resistance. Without this resistor, the current flowing through the diode would be excessive, causing it to overheat and burn out almost instantly. The resistor ensures the current stays within the LED's safe operating limits.
5. How do the V-I characteristics of an LED explain its function as a light source?
The Voltage-Current (V-I) graph of an LED shows that, like a standard diode, it allows current to flow easily only in one direction (forward bias). However, it has a specific threshold voltage (or knee voltage) that must be overcome before any significant current flows. Once this voltage is exceeded, current increases sharply, and the LED begins to emit light. The intensity of this light is directly proportional to the amount of forward current passing through it. This characteristic is the key to its function: controlling the forward current allows for precise control over the brightness of the light emitted.
6. From a Physics perspective, what makes the different colours of LEDs a good example of quantum mechanics?
The colour of an LED is a direct, practical demonstration of the quantum mechanical principle that energy is quantised. The colour of the emitted light is determined by the energy band gap of the semiconductor material. When an electron recombines with a hole, it releases a single photon with energy equal to this band gap. Different materials have different band gaps, leading to different colours: for instance, Gallium Arsenide Phosphide (GaAsP) for red light and Gallium Nitride (GaN) for blue light. This directly illustrates that light is emitted in discrete energy packets (photons), a foundational concept of quantum physics.
7. Can an LED work if it is connected in reverse bias?
No, an LED will not emit light if it is connected in reverse bias. In this configuration, the p-n junction's depletion region widens, which prevents any significant current from flowing through the device. Since light emission is a result of electron-hole recombination, which requires a forward current, no light is produced. Applying a reverse voltage greater than the LED's specified breakdown voltage can also cause permanent damage to the component.
