UPSC CAPF AC 2025 Paper 1 · Question 106
Question 106 of the UPSC CAPF (AC) 2025 Paper I (3 August 2025). Try it first, then open the answer and explanation.
Which one of the following principles of physics is primarily used in sonography, a medical diagnostic process?
- Resonance
- Superposition of waves
- Doppler effect
- Standing wave
भौतिकी के निम्नलिखित किस सिद्धांत का उपयोग मुख्य रूप से सोनोग्राफी में किया जाता है, जो एक चिकित्सा निदान प्रक्रिया है?
- अनुनाद (Resonance)
- तरंगों का अध्यारोपण (Superposition of waves)
- डॉप्लर प्रभाव (Doppler effect)
- अप्रगामी तरंग (Standing wave)
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Answer: (3) Doppler effect
उत्तर: (3) डॉप्लर प्रभाव (Doppler effect)
Sonography sends high-frequency ultrasound into the body and analyses the returning echoes; the change in frequency of echoes from moving targets such as flowing blood or a beating foetal heart (the Doppler effect) is used in Doppler sonography to measure the speed and direction of flow. Basic imaging relies on reflection of ultrasound (echoes), which is not among the options; of those given, the Doppler effect is the principle used, while resonance, superposition and standing waves are not the basis of the technique.