GS Paper III — Q16
The Nobel Prize in Physics of 2014 was jointly awarded to Akasaki, Amano and Nakamura for the invention of Blue LEDs in 1990s…
The Nobel Prize in Physics of 2014 was jointly awarded to Akasaki, Amano and Nakamura for the invention of Blue LEDs in 1990s. How has this invention impacted the everyday life of human beings? (Answer in 250 words)
हिंदी में प्रश्न पढ़ें
वर्ष 2014 में भौतिक विज्ञान में नोबेल पुरस्कार संयुक्त रूप से आकासाकी, अमानो तथा नाकामुरा को 1990 के दशक में नीली एल.ई.डी. के आविष्कार के लिए प्रदान किया गया था । इस आविष्कार ने मानव-जाति के दैनंदिन जीवन को किस प्रकार प्रभावित किया है ? (250 शब्दों में उत्तर दीजिए)
Model answer
Drafted with AI by UPSC Answer Check against this question's marking rubric, to the 250-word length. UPSC does not publish answers for Mains — this is one way to score well, not an official key. How we build rubrics and answers.
(a) Why blue mattered: Red and green LEDs existed earlier; blue completed the RGB set, enabling full-colour displays, and with a phosphor coating it produced efficient white light, turning LEDs from indicators into a general light source.
(b) Lighting and energy: LEDs use about 85% less energy than incandescent bulbs and last up to 25 times longer, cutting household bills and national demand, and emit little heat, which makes homes, offices and street lighting safer. In India, UJALA's distribution of over 36 crore LED bulbs has saved about 4,700 crore kWh a year, easing peak load, reducing coal-based generation and carbon emissions.
(c) Displays and communication: Blue LEDs made bright, thin, low-power screens practical, so smartphones, LED televisions, laptops, tablets and outdoor advertising rely on them, making information and entertainment more portable.
(d) Health, sanitation and agriculture: Blue and UV-LEDs support water purification, sterilisation of medical equipment and phototherapy for neonatal jaundice. LED grow lights support controlled-environment farming, and Li-Fi is an emerging application.
How this answer will be evaluated
Framework: Technology: why it matters, use, benefit, risk, policy
What earns full marks: Detailed, specific impacts on energy, health, and industry with clear examples.
Evaluation rubric
Each sub-part is marked on its own, against the marks and word limit printed on the paper.
- The answer Explain the specific impacts of Blue LED invention on daily human life. 15 marks · 250 words
explain— definition/context → points in order → small example → short close
Must cover
- Energy efficiency and reduced electricity consumption
- Enabling white light for general illumination
- Impact on display technologies (TVs, screens)
- Health and safety benefits (reduced heat, no UV)
Loses marks
- Focusing on the history of the Nobel Prize
- Vague generalities about 'technology is good'
- Ignoring the specific role of the 'Blue' component
Earns more
- Mention of solid-state lighting replacing incandescent
- Impact on agriculture (grow lights)
- Longer lifespan and lower maintenance costs
- Environmental impact (reduced carbon footprint)
Extra mark
- Specific statistic on energy savings (e.g., 80% efficient)
- Mention of specific applications like medical lighting
What "Explain" is asking you to do
Make the working of something clear — what sets it off, what follows from what, and what it produces. Explain is the Commission's mechanism word: it dominates the technical papers and the “explain why” stems, where the marks sit in the causal chain and not in the label.
Structure that answers it
State what it is → the initiating condition → the chain of cause, step by step → an instance where it plays out → what the chain produces
Where marks are lost
Describing what something looks like instead of why it works that way. Naming the stages without linking them reads as description too.
Practice this exact question
Write your answer and it is marked point by point against the model answer above — what you covered, what you missed, what you got wrong.
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