UPSC CAPF (AC) 2026 Paper I · Question 111

Question 111 of the UPSC CAPF (AC) 2026 Paper I (19 July 2026). Try it first, then open the answer and explanation.

1. CAPF 2026 · P-I · Q111 · General Science · Physics

   Sound Navigation and Ranging (SONAR) is used to detect underwater objects. For this, its transmitter produces

   1. microwaves
   2. visible light
   3. ultrasonic waves
   4. infrared radiation

   अंतर्जलीय वस्तुओं का पता लगाने के लिए ध्वनि नैविगेशन और रेंजिंग (SONAR) का प्रयोग किया जाता है। इसके लिए, इसका ट्रांसमीटर क्या उत्पन्न करता है?

   1. सूक्ष्मतरंगें (microwaves)
   2. दृश्य प्रकाश (visible light)
   3. पराश्रव्य तरंगें (ultrasonic waves)
   4. अवरक्त विकिरण (infrared radiation)
   Show answer

   Answer: (3) ultrasonic waves

   उत्तर: (3) पराश्रव्य तरंगें (ultrasonic waves)

   SONAR sends out pulses of ultrasonic waves and times the echo reflected from the object; distance = (speed of sound in water × time)/2. Microwaves, visible light and infrared are electromagnetic waves that seawater absorbs within a short distance, so they cannot be used to locate objects far under water.

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