1.2 What Is An Echo Essay

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Year 9 Physics 2015 Name : shani Lewis Date: 21.08.2015
Q Marks
1 2 What is an echo? Explain why an empty room will produce one? [2 marks]

An echo is a reflection of sound, arriving at the listener sometime after the direct sound. A true echo is a single reflection of the sound source. The time delay is the extra distance divided by the speed of sound.

2 5 Explain how sonar works and why it is useful. Provide at least one diagram or picture. [5 marks]

Sonar is simply making use of an echo. When an animal or machine makes a noise, it sends sound waves into the environment around it. Those waves bounce off nearby objects, and some of them reflect back to the object that made the noise. 3 5 Pick an example of radar and explain how
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(Children can generally hear higher-pitched sounds than their parents, because our ability to hear high frequencies gets worse as we get older.) Speaking more scientifically, we could say that the sounds we can perceive have a frequency ranging from 20–20,000 hertz (Hz). A hertz is a measurement of how often something vibrates and 1 Hz is equal to one vibration each second. The human voice makes sounds ranging from a few hundred hertz to a few thousand hertz. Ultrasound is usually used to track progress on things such as an unborn child’s growth whilst in the womb, or growth of cancer tumours and much more.
5 3 Describe ONE of the following: Sonagraph, 3D ultrasound, Doppler ultrasound [3 marks]

3D ultrasound is a medical ultrasound technique, often used in obstetric ultrasonography (during pregnancy), providing three-dimensional images of the fetus. There are several different scanning modes in medical and obstetric ultrasound. The standard common obstetric diagnostic mode is 2D scanning.[1] In 3D fetal scanning, however, instead of the sound waves being sent straight down and reflected back, they are sent at different angles.

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