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Q21 (NDA-II/2018) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Electricity and magnetism Answer Verified

The full form of LED is

Result
Your answer: —  Â·  Correct: A
Explanation

The full form of LED is Light Emitting Diode [2]. It is an optoelectronic semiconductor device that converts electrical energy into light energy through the principle of electroluminescence. Structurally, an LED is a specially doped p-n junction diode that emits light in either the visible or infrared region when forward biased. Unlike traditional incandescent lamps that use a filament, LEDs are directional light sources that are more energy-efficient, durable, and have a longer lifespan [1]. In an electrical circuit, an LED has two terminals: a positive terminal (longer wire) and a negative terminal (shorter wire), allowing current to flow in only one direction [5]. Because they do not contain toxic materials like mercury and consume significantly less power, they are widely promoted for modern lighting solutions [1].

Sources

  1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 11: Light: Shadows and Reflections > SCIENCE AND SOCIETY > p. 154
  2. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 3: Electricity: Circuits and their Components > LED Lamp > p. 27
  3. [5] Science-Class VII . NCERT(Revised ed 2025) > Chapter 3: Electricity: Circuits and their Components > In a Nutshell > p. 37
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