Physics: Optics and Sound: UPSC Previous Year Questions (Science and Technology)
1 previous year UPSC Prelims question on Physics: Optics and Sound (Science and Technology). Choose an option to see the answer and explanation.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 1–1 of 1 question
UPSC 2009Science and Technology · Physics: Optics and Sound
Q1. Which one of the following types of waves are used in a night vision apparatus?
Explanation
Option (c) is correct: Night vision apparatus detects infrared waves emitted by objects as heat. Warmer objects emit more infrared radiation which is invisible to the human eye but can be captured and converted into a visible image by night vision devices. Infrared waves are electromagnetic waves with wavelengths longer than visible light but shorter than microwaves, typically used in thermal imaging, night vision, and remote sensing. Options (a) and (b) are incorrect: Microwaves are used in cooking and radar systems and radio waves are used for communication in broadcasting, mobile phones, and satellite transmissions.
Answer key for these questions
Q
UPSC year
Correct answer
1
2009
(c) Infrared waves
Frequently asked questions
How many previous year UPSC questions are there on Physics: Optics and Sound?
This page covers 1 previous year UPSC Prelims GS Paper-I questions on Physics: Optics and Sound (Science and Technology), asked from 1996 to 2009. Each has the correct answer and an explanation.
How should I use previous year UPSC questions for Prelims?
Attempt each question first, then open the answer and read the explanation for every option. Repeat by chapter, and track which statements UPSC reuses across years. Previous year questions show the exam pattern and difficulty level.
Which years are covered for Physics: Optics and Sound?
Questions on Physics: Optics and Sound (Science and Technology) are available for 8 years, from 1996 to 2009. Use the Year filter to practise a single paper.
