Product Information
Light-Emitting Diode (LED)
Understand how a semiconductor converts electrical energy into light. Explore LED polarity, forward bias, electroluminescence and basic electronic circuit applications.
What Is a Light-Emitting Diode?
A Light-Emitting Diode (LED) is a semiconductor device that produces light when electric current flows through it in the forward direction. It is a type of p-n junction diode that works on the principle of electroluminescence. LEDs are widely used as indicator lights, display elements and lighting components. In educational laboratories, they help students understand semiconductor behaviour and electronic circuit fundamentals.
How Does an LED Work?
01. Forward Bias
The anode is connected to the positive supply and the cathode to the negative supply through a suitable current-limiting arrangement.
02. Charge Carrier Movement
Electrons and holes move towards the p-n junction under forward bias.
03. Light Generation
Electron-hole recombination releases energy in the form of photons in a light-emitting semiconductor.
04. Visible Output
The LED emits light according to its semiconductor material and design. Different materials produce different wavelengths and colours.
ElectroluminescenceThe process in which electrical energy is converted into light through the operation of a semiconductor device is called electroluminescence.
Important LED Terminals and Polarity
Anode (+)
The positive terminal of an LED. In many standard through-hole LEDs, the longer lead indicates the anode.
Cathode (-)
The negative terminal. In many standard through-hole LEDs, the shorter lead and flat casing edge indicate the cathode.
Lead length and casing markings are common identification methods, but should be verified against the component datasheet or with a suitable diode test before connection.
Basic LED Experiment – Step by Step
STEP 01 Identify the TerminalsDetermine the anode and cathode before making the circuit connections.
STEP 02 Connect the CircuitConnect the LED in forward bias with a suitable series current-limiting resistor.
STEP 03 Apply SupplyUse a suitable regulated DC source and remain within the component ratings.
STEP 04 Observe Light OutputObserve the LED illumination when the circuit is correctly connected.
STEP 05 Measure Voltage and CurrentRecord suitable forward voltage and current readings using appropriate meters.
STEP 06 Study V-I CharacteristicsCompare readings and plot a forward voltage versus current graph.
LED Technical Information
Product NameLight-Emitting Diode (LED)Component TypeSemiconductor DiodeOperating PrincipleElectroluminescenceJunction Typep-n JunctionTerminalsAnode and CathodeOperating BiasForward Bias for normal light emissionAvailable ColourConfirm available colours with PSAWPackage / SizeConfirm with PSAW Laboratory EquipmentsForward Voltage and Current RatingRefer to the selected LED datasheetEducational Benefits of Studying LEDs
Semiconductor Fundamentals
Introduces students to p-n junction devices and charge carrier behaviour.
Practical Circuit Skills
Develops understanding of circuit connections, polarity and current limiting.
Electrical Measurement
Supports experiments involving voltage, current and V-I characteristics.
Light and Energy Concepts
Demonstrates conversion of electrical energy into light energy.
Where Are LEDs Used?
Electronic IndicatorsUsed to indicate power status and operating conditions in electronic devices.
Digital DisplaysUsed in display systems, numeric indicators and electronic panels.
Lighting SystemsUsed in lamps, bulbs, decorative lighting and illumination products.
Educational CircuitsUsed in school projects, electronic experiments and basic circuit demonstrations.
Quality Inspection Before Laboratory Use
- Inspect the LED body and semiconductor package for visible damage.
- Check the anode and cathode identification.
- Confirm the forward voltage and current rating from the datasheet.
- Check that the LED emits light under the specified forward-bias conditions.
- Inspect both leads or terminals for bending, corrosion or damage.
- Use a suitable series resistor or current-controlled supply.
- Verify the colour and package type against the purchase requirement.
These are recommended inspection checks, not a claim of independent certification or completed testing by PSAW.
LED vs Ordinary Diode – What Is the Difference?
Feature LED Ordinary Diode Main Function Emits light Controls current direction Forward Bias Produces light Conducts current Typical Application Indicators and lighting Rectification and protection Energy Output Electrical to light and heat Primarily electrical conduction Explore More Laboratory Subcategories
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1. What is a Light-Emitting Diode (LED)?
An LED is a semiconductor p-n junction device that emits light when operated under suitable forward-bias conditions.
2. What is the working principle of an LED?
An LED works on electroluminescence. When electrons and holes recombine in the semiconductor junction, energy is released in the form of photons.
3. Why does an LED glow in forward bias?
Forward bias allows charge carriers to cross the junction and recombine. This recombination produces light in the LED semiconductor material.
4. What are the positive and negative terminals of an LED?
The positive terminal is called the anode and the negative terminal is called the cathode. Check the component markings or datasheet to identify them correctly.
5. Why is a resistor used with an LED?
A series resistor limits the current flowing through the LED and helps prevent damage caused by excessive current.
6. What is the V-I characteristic of an LED?
It is the relationship between the forward voltage applied to the LED and the resulting forward current. It is studied by recording voltage and current readings under controlled conditions.
7. Does LED colour depend on semiconductor material?
Yes. The semiconductor material and its energy band gap influence the wavelength and colour of the emitted light.
8. What is the difference between an LED and a normal diode?
Both are semiconductor diodes, but an LED is designed to emit light under forward bias, whereas an ordinary diode is generally used for electrical conduction, rectification or circuit protection.
9. Can an LED be connected directly to a battery?
Only when the supply and current are properly controlled according to the LED rating. A suitable current-limiting resistor or driver is normally required.
10. Where can I buy an LED for a physics laboratory?
Contact PSAW Laboratory Equipments to enquire about available LED components, colours, package types, technical specifications and pricing.
Looking for LED Components for Your Laboratory?
Get in touch with PSAW Laboratory Equipments for Light-Emitting Diodes and other educational electronic components. Share your laboratory requirements to enquire about available options and product details.
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Light-Emitting Diode (LED) for Physics Laboratory
The Light-Emitting Diode (LED) is a semiconductor electronic component that emits light when connected in forward bias. It converts electrical energy into light through the process of electroluminescence. This component is useful for studying semiconductor behaviour, diode polarity, forward bias and basic electronic circuits in physics and electronics laboratories. Contact PSAW Laboratory Equipments for available colours, sizes and technical specifications.