Aviation Electronics Technician 1 - Historic Naval Ships Association

4-12. Sonar transmission losses can becaused by1. low-frequency pinging signals2. low transducer power output3. high foreign matter content ofwater4. weak pinging signals4-13. Assume that the crew on a destroyerwhich was conducting passive sonaroperations, witnessed a surfacemine explosion at a distance ofseveral hundred yards. If thesonar equipment detected the sound4 seconds after the explosion,approximately how many seconds wererequired for the sound travelingthrough the air to reach the crew?1. 1 sec2. 8 sec3. 16 sec4. 4 sec4-14. What is the effect on a sound wavetraveling in the ocean when thewave strikes the sea surface?1. Downward reflection2. Downward refraction3. Upward reflection4. Upward refraction4-15. At what angle must a sound beamstrike the side of a submarine toproduce an echo?1. 180°2. 90°3. 45°4. 0°4-16. Of the following surfaces, whichone will cause the LEAST amount ofreflections?1. Calm sea2. Rough and rocky bottom3. Sandy bottom4. Soft and muddy bottom4-17. Most individual sound reflectionsare sharp and clear, but vary inintensity. Why does reverberationappear as a continuous sound?1. The sound waves are reflectedat different intensities fromvarious objects2. The individual reflectionsintermingle, and set up soundwaves of different speeds3. The individual reflectionsoccur at different distancesfrom the sonar, and arrive atdifferent times4. The sound waves are reflectedat different frequencies fromvarious objects4-18. Which of the following conditionswill cause the greatest amount ofreverberation in deep water?1. A smooth ocean surface2. A sudden change in waterdensity3. Choppy waves on the surface4. A sandy ocean bottom4-19. The factor that will most likelydetermine maximum sonar range whensound propagation conditions areideal is1. absorption2. refraction3. reverberation4. divergence4-20. Varying temperature differences inthe ocean have which of thefollowing effects on a sound beamtraveling therein?1. Bends and distorts only2. Splits and distorts only3. Bends and splits only4. Splits, bends, and distorts4-21. The bending of a sound beam when itpasses from a medium of giventemperature to a medium ofdifferent temperature is known as1. refraction2. deflection3. reflection4. diffraction24