Chapter 12 SOUND

How can Bat detected the navigation and location of food in the dark?

Bats search out prey and fly in dark night by emitting and detecting reflections of ultrasonic waves. The high-pitched ultrasonic squeaks of the bat are reflected from the obstacles or prey and returned to bat’s ear.The nature of reflections tells the bat where the obstacle or prey is and what it is like.Porpoises also use …

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A ship sends out ultrasound that returns from the seabed and is detected after 3.42 s. If the speed of ultrasound through seawater is 1531 m/s, what is the distance of the seabed from the ship?

Solution:Given,Time between transmission anddetection, t = 3.42 s. Speed of ultrasound in sea water, v = 1531 m/sDistance travelled by the ultrasound = 2 × depth of the sea = 2dwhere d is the depth of the sea. 2d = speed of sound × time = 1531 m/s × 3.42 s = 5236 m d …

A ship sends out ultrasound that returns from the seabed and is detected after 3.42 s. If the speed of ultrasound through seawater is 1531 m/s, what is the distance of the seabed from the ship? Read More »

SONAR

The acronym SONAR stands for Sound Navigation And Ranging. Sonar is a device that uses ultrasonic waves to measure the distance, direction and speed of underwater objects. Sonar consists of a transmitter and a detector and is installed in a boat or a ship, The transmitter produces and transmits ultrasonic waves. These waves travel through …

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USES OF MULTIPLE REFLECTION OF SOUND

USES OF MULTIPLE REFLECTION OF SOUND Megaphones or loudhailers, horns, musical instruments such as trumpets and shehanais, are all designed to send sound in a particular directionwithout spreading it in all directions, In these instruments, a tube followed by a conical opening reflects sound successively to guide most of the sound waves from the source …

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A person clapped his hands near a cliff and heard the echo after 2 s. What is the distance of the cliff from the person if the speed of the sound, v is taken as 346 m/ s?

Solution:Given,Speed of sound, v = 346 m s–1Time taken for hearing the echo,t = 2 sDistance travelled by the sound= v × t = 346 m s–1 × 2 s = 692 mIn 2 s sound has to travel twice thedistance between the cliff and the person. Hence, the distance betweenthe cliff and the person …

A person clapped his hands near a cliff and heard the echo after 2 s. What is the distance of the cliff from the person if the speed of the sound, v is taken as 346 m/ s? Read More »

REVERBERATION

A sound created in a big hall will persist by repeated reflection from the walls until it is reduced to a value where it is no longeraudible. The repeated reflection that results in this persistence of sound is called reverberation. In an auditorium or big hall excessive reverberation is highly undesirable.To reduce reverberation, the roof …

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ECHO

If we shout or clap near a suitable reflecting object such as a tall building or a mountain,we will hear the same sound again a little later. This sound which we hear is called an echo. The sensation of sound persists in our brain for about 0.1 s. To hear a distinct echo the time …

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