SONAR stands for
- (a)Sonographic Natural Ranging
- (b)Simple Operational Navigation Ranging
- (c)Sound Navigation and Ranging
- (d)Simple Operational Natural Ranging
Correct — C, Sound Navigation and Ranging. SONAR is a technique that uses ultrasonic sound waves to detect and locate underwater objects and to measure the depth of the sea. It sends out a pulse of sound, and by timing the echo that bounces back from the seabed or an object, it works out the distance, or range.
- (a)Sonographic Natural Ranging — Not the correct expansion — the 'SO' in SONAR stands for 'Sound', not 'Sonographic', and there is no 'Natural' in the acronym.
- (b)Simple Operational Navigation Ranging — Incorrect expansion; the first letters do not stand for 'Simple Operational'. The correct first word is 'Sound'.
- (d)Simple Operational Natural Ranging — Wrong on two counts — neither 'Simple Operational' nor 'Natural' appears in the real acronym, which is Sound Navigation and Ranging.
SONAR (Sound Navigation and Ranging) locates underwater objects by emitting pulses of ultrasonic sound and detecting their echoes. The distance to an object equals the speed of sound in water multiplied by the time taken for the echo to return, divided by two (since the sound travels to the object and back).
Radio and light waves are strongly absorbed by water, so ships and submarines use sound instead, which travels well through it. The method — echo-ranging — is the same principle bats use for echolocation, and it is the underwater cousin of RADAR, which does the same job in air using radio waves.
- SONAR stands for Sound Navigation and Ranging.
- It uses ultrasonic (high-frequency) sound waves, which travel well through water.
- Distance to an object equals the speed of sound in water multiplied by the echo time, divided by two.
- It is used to measure sea depth (bathymetry) and to detect submarines, shoals of fish and shipwrecks.
- Ship or submarine emits an ultrasonic sound pulse
- The pulse travels through water and strikes the seabed or an object
- An echo reflects back to the receiver
- Distance = (speed of sound in water x echo time) / 2
Timing the returning echo gives the range — the same echo principle bats use to navigate.
- Forgetting to divide by two — the sound travels to the object and back, so the one-way distance is half the total path.
- Confusing SONAR (sound waves, underwater) with RADAR (radio waves, in air).
Asked as the full form of SONAR, or as which principle or type of wave is used to measure sea depth and detect submarines.
No directly related past PYQ was found.
- practice — not a real PYQ
SONAR is used mainly to
- (a)measure air pressure
- (b)detect underwater objects and measure sea depth
- (c)photograph the sea surface
- (d)measure temperature of the sea
Answer(b) detect underwater objects and measure sea depth, using the echo of ultrasonic sound.
- practice — not a real PYQ
The type of waves used in SONAR are
- (a)radio waves
- (b)light waves
- (c)ultrasonic sound waves
- (d)X-rays
Answer(c) ultrasonic sound waves, which travel well through water.