निम्नलिखित कथनों पर विचार कीजिए : 1. ऑटोमोबाइल और एयरक्राफ्ट में प्रयुक्त होने वाले अवयवों के विनिर्माण में कार्बन तंतुओं का इस्तेमाल होता है। 2. कार्बन तंतु एक बार प्रयुक्त होने पर पुनर्चक्रित नहीं किए जा सकते। उपर्युक्त कथनों में से कौन-सा/से सही है/हैं?

(d) न तो 1 और न ही 2

निम्नलिखित क्रियाओं पर विचार कीजिए : 1. कार क्रैश/टक्कर का, जिससे एयरबैग लगभग तुरंत फैल जाते हैं, पता लगाना 2. लैपटॉप अचानक धरातल पर गिर पड़ने का, जिससे हार्ड ड्राइव तुरंत बंद हो जाता है, पता लगाना 3. स्मार्टफोन के झुकाव का, जिससे पोर्ट्रेट और लैंडस्केप मोड के बीच प्रदर्शन (डिस्प्ले) घूम जाता है, पता लगाना उपर्युक्त में से कितनी क्रियाओं में, त्वरणमापी (ऐक्सेलरोमीटर) के प्रकार्य की आवश्यकता है?

(d) किसी में भी नहीं

प्रश्न यूपीएससी के हिंदी प्रश्नपत्र से · व्याख्या अभी अंग्रेज़ी में

Prelims · Science & technology · 28 questions

Physics & chemistry in everyday life

Every UPSC Prelims question on this topic, 2016–2026, newest first. Tap an option to check yourself; the answer and explanation open below it.

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UPSC syllabus: “General Science.” Sub-topics in the detailed syllabus →

Prelims 2023 · Q53

Easy

निम्नलिखित कथनों पर विचार कीजिए :

1.ऑटोमोबाइल और एयरक्राफ्ट में प्रयुक्त होने वाले अवयवों के विनिर्माण में कार्बन तंतुओं का इस्तेमाल होता है।
2.कार्बन तंतु एक बार प्रयुक्त होने पर पुनर्चक्रित नहीं किए जा सकते।

उपर्युक्त कथनों में से कौन-सा/से सही है/हैं?

Read this question in English

Consider the following statements:

1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.

2. Carbon fibres once used cannot be recycled.

Which of the statements given above is/are correct?

(a) 1 only · (b) 2 only · (c) Both 1 and 2 · (d) Neither 1 nor 2

उत्तर और व्याख्या · explanation in English

Answer: (a) केवल 1

Only statement 1 is correct. Carbon fibre is a light, strong material used in vehicle bodies and in aircraft parts, and it can be recovered from used composites and reused, so it is not a one-time material.

✓ 1. Carbon-fibre composites go into vehicle chassis, body panels and doors, and into aircraft fairings, fuselages and floor panels. Their strength for low weight is the reason.
✗ 2. Carbon fibre can be recycled. Recycled fibre is already used in new products and needs far less energy than making virgin fibre, which is highly energy intensive.

Remember · Carbon fibre is strong and light, used in cars and aircraft, and is recyclable: recovered fibre is reused in new composites.

Sources

Bandwidth Study on Energy Use and Potential Energy Saving Opportunities in Carbon Fiber Reinforced Polymer Composites (US Department of Energy) ↗ “1) Automotive lightweighting (e.g., vehicle chassis, body, doors); 2) Compressed gas storage (e.g., hydrogen fuel tanks for electric vehicles); 3) Wind turbines (e.g., lighter and longer turbine blades); and 4) Aerospace (e.g., aircraft fairings, fuselages, floor panels). … Use of recycled carbon fiber content in products reduces energy requirements, as production of virgin carbon fibers is highly energy intensive.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q54

X-Ray · Core #43 Easy

निम्नलिखित क्रियाओं पर विचार कीजिए :

1.कार क्रैश/टक्कर का, जिससे एयरबैग लगभग तुरंत फैल जाते हैं, पता लगाना
2.लैपटॉप अचानक धरातल पर गिर पड़ने का, जिससे हार्ड ड्राइव तुरंत बंद हो जाता है, पता लगाना
3.स्मार्टफोन के झुकाव का, जिससे पोर्ट्रेट और लैंडस्केप मोड के बीच प्रदर्शन (डिस्प्ले) घूम जाता है, पता लगाना

उपर्युक्त में से कितनी क्रियाओं में, त्वरणमापी (ऐक्सेलरोमीटर) के प्रकार्य की आवश्यकता है?

Read this question in English

Consider the following actions:

1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously

2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive

3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode

In how many of the above actions is the function of accelerometer required?

(a) Only one · (b) Only two · (c) All three · (d) None

उत्तर और व्याख्या · explanation in English

Answer: (c) सभी तीन

All three actions need an accelerometer. An accelerometer is a sensor that measures changes in motion, and a crash, a free fall and a tilt each show up as a change in acceleration that the device can read.

✓ 1. Airbag systems decide whether to deploy from how abruptly the car's speed changes, which an accelerometer measures.
✓ 2. Drives in laptops use an accelerometer to sense free fall; the drive then parks its read-write head or powers down before impact to avoid damage.
✓ 3. A phone's accelerometer senses the direction of gravity, so it knows how the phone is tilted and rotates the display between portrait and landscape.

Remember · An accelerometer senses changes in motion. It triggers airbags, protects laptop drives in free fall and rotates phone screens.

Sources

New Accelerometer Calibration Service to Start Soon (National Institute of Standards and Technology, US) ↗ “Accelerometers, which detect changes in motion, are perhaps most familiar as the sensors that tell your mobile phone screen to rotate or determine whether automotive airbags should deploy based on how abruptly the car's speed changes.”
US Patent 7,369,345, Mobile hard disk drive free fall detection and protection (USPTO; text via Google Patents) ↗ · reference work “after a free fall event is detected, a signal is sent from the accelerometer to a processor to cause a signal to be sent to the voice coil motor to park the actuator arm.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q62

X-Ray · Core #31 Medium

पृथ्वी के वायुमंडल के संदर्भ में, निम्नलिखित कथनों में से कौन-सा एक सही है?

Read this question in English

With reference to the Earth's atmosphere, which one of the following statements is correct?

(a) The total amount of insolation received at the equator is roughly about 10 times of that received at the poles. · (b) Infrared rays constitute roughly two-thirds of insolation. · (c) Infrared waves are largely absorbed by water vapour that is concentrated in the lower atmosphere. · (d) Infrared waves are a part of visible spectrum of electromagnetic waves of solar radiation.

उत्तर और व्याख्या · explanation in English

Answer: (c) अवरक्त तरंगें निचले वायुमंडल में संकेंद्रित जलवाष्प द्वारा वृहद् रूप से अवशोषित होती हैं।

Statement (c) is correct: water vapour, ozone and other gases in the lower atmosphere (the troposphere) absorb much of the near-infrared radiation passing through. The other options misstate insolation values or the nature of infrared light.

✓ (c) NCERT says water vapour, ozone and other gases within the troposphere absorb much of the near-infrared radiation. Water vapour is concentrated in the lower atmosphere.
✗ (a) NCERT gives insolation at the surface as about 320 W/m2 in the tropics and about 70 W/m2 at the poles, a ratio of under five, and it says the equator receives less than the tropics. Ten times is far too high.
✗ (d) Infrared waves lie just beyond the visible spectrum; the human eye cannot see them. They are not part of the visible spectrum.

Remember · In the troposphere, water vapour, ozone and other gases absorb much of the near-infrared radiation. Insolation is about 320 W/m2 in the tropics and 70 W/m2 at the poles.

📘 Read it in NCERT: Class 11 Fundamentals of Physical Geography, Ch 8 (practise this chapter) · Class 11 Fundamentals of Physical Geography, Ch 8 (practise this chapter)

Sources

NCERT Class 11 · Fundamentals of Physical Geography, Chapter 8 “Within the troposphere water vapour, ozone and other gases absorb much of the near infrared radiation.”
NCERT Class 11 · Fundamentals of Physical Geography, Chapter 8 “The insolation received at the surface varies from about 320 Watt/m2 in the tropics to about 70 Watt/m2 in the poles.”
Infrared Waves (NASA Science, Electromagnetic Spectrum) ↗ “the human eye cannot see it, but humans can detect it as heat. A remote control uses light waves just beyond the visible spectrum of light—infrared light waves—to change channels on your TV.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

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