Answer Happy

here are the questions :
EXPERIMENT NO. 4 SONAR OBJECTIVES To demonstrate sound propagation with the use of sonar. • To interpret data with the use of statistical methods on dealing with errors. BACKGROUND Sonar (sound navigation and ranging) is a technique that uses sound propagation for navigation, object detection and mapping. There are two types of sonar, passive sonar. listening for incoming sound, and active sonar: transmitting sound pulses and receiving echoes. Active sonar is what will be used in this activity with the use of your mobile phone (speaker and microphone) as illustrated in Fig. 1. Initial sound wave echo shield DO Transmitter & receiver speed distance time flat and hard reflector VE Dr reflected sound wave fecho) distance ( sound travels 2x the distance Fig. 1. Illustration of sound propagation (transmission and reflection). To measure the distance of an object using sonar, the time from pulse transmission to reception is measured and converted into a range using the known speed of sound (343 m/s), and it is given in this relation: da

Where v as the speed of sound in air (343 m/s), t as the time of pulse transmission to reception, and d as distance of an object. The total distance traveled by the sound wave is 2d, i.e., from transmission to reception. More background information about this experiment can be found in your Phyphox App in the "Experiment info" of the "Sonar" experiment under the "Acoustics" section. And you may visit this wiki page: https://phyphox.org/wiki/index.php/Experiment: Sonar to know more on the possible problems that you will encounter and recommended resolutions. MATERIALS / TOOLS • Mobile phone with Phyphox mobile application • PC / Laptop (control/monitor and plotting: https://phyphox.org/remote-controll) • Box / echo shield for the mobile phone (e.g. foam, box container that can fit your mobile phone, which shields all directions from phone except the speaker and microphone location). NOTE: Try different materials with different sizes, which will show minimal noise (unwanted ripples or peaks) in your graph. • Sound reflector material (i.e. hard and flat material, e.g. tray) • Measuring tape • Support for the reflector that will hold it in a vertical position (optional) PROCEDURE Preliminary: • Watch the video on how to use your smartphone as a sonar for this experiment in this link 34701HE0&feature=youtu.be. Since you are going to use your mobile phone as sensor in this experiment, you need a second device (such as a laptop or tablet with internet browser) as control and monitor screen. Instructions can be found in this link https://phyphox.org/remote- control/ and connection instructions in this link ypn9M. Do this experiment on a flat surface (e.g. floor). 1. Under the Phypox app, connect your mobile phone with your laptop or tablet (instructions can be found on the second and third links under the Preliminary section) This second device would serve as your monitor and control during the duration of this experiment. If you do not have a second device, you would need a support stand for the target so you can do this experiment. 2. Place your mobile phone inside the box. Making sure that the microphone (receiver) is placed facing the box opening.

Fig. 2. Sample setup (3) 3. Spread the measuring tape in such a way that it will be convenient for you to manually measure the distance from your mobile phone to the flat object (to echolocate). The mobile phone microphone (receiver) is assumed to be the reference point. Take note of the predefined distances in your data sheet. Sample setup configuration is shown in Fig. 2. 4. Take a photo of your setup including the flat object as target. You may use some marker in place of your mobile phone so you can use your mobile phone's camera. 5. Under the "Echo Location" tab, make sure that the correct speed of sound (343 m/s in air) is entered. 6. You will refer to the "Normalized to spherical surface" plot to check the distance of your target. Once measuring the highest peak on the graph should correspond approximately to the actual distance of the target. Some small ripples (unwanted peaks) may be present as noise depending on how good your setup is and on your environment noise level. TIPS: • Check if your setup is good enough by pressing the "start" button to start acquiring data and placing the target object near your phone. Gradually increase the distance of your target object from your phone and check if you are getting the correct distance peak with smaller noise (unwanted ripples). • You may want to change your box or do the experiment with lesser environmental noise if the data is still too noisy (meaning, many unwanted ripples or peaks are still present that it makes it too hard to distinguish the main peak, i.e., the supposed target's location). Remember that the sound is moving in 360 direction, and the type of material and size of the material used as barrier are important. Also, since

you are measuring reflected sound waves, noisy environment could affect your measurement 7. Once you have achieved a setup with minimal noise, press the "Timed Run" option to set the desired "Start delay(s) time and "Experiment duration(s)". TIP: • The delay should be enough time before you expect the measurement to begin, and the experiment duration should be enough time so you will get a good approximate peak at the target's location (reference: actual distance). Configure several times to optimize your setup. As an example - delay. 3 s, experiment duration: 10 s. 8. Place your object at the initial distance (50 cm) and start your data collection. 9. After your measurement, tap the "Normalized to spherical surface" plot. Select the "Pick data and pinpoint the main peak to know the measurement value of the object's distance. 10. Record your result and print-screen your plots from the Phyphox App both from "Echo Location" and "Timing" tabs. Do this for every remaining distance mentioned: 100-250 cm at 50 cm interval. REFERENCES 1. R.W.T.H.A. University. Phyphox [Online]. Available: https://phyphox.org/download/. 2. R.W.T.H.A. University Phyphox [Online]. Available: 3. J. Lopez, Sonar experiment. DLSU, 2020.

Names: Date Performed: Course Code & Section: DATA SHEET 50 100 150 200 250 Distance (cm) Distance obtained from Phyphox (cm) % Error Distance of the target object, which is ideally the main peak or highest peak from the graph. A. Insert the image of your setup. B. Insert the print-screened plots of your result from Phyphox (echo location and Timing).

QUESTIONS 1. Is the measured distance (Phyphox) differs from the actual value? Elaborate your answer and include the discussion of errors (if necessary). 2. From the relationship between (sound) velocity (v), distance (d) and time (t) in Eq. 1, solve for the total time it takes for the sound waves (chirp) to travel from your phone to your target at 100 cm and back to your phone. Use both your measured data and actual data and get their % difference. Be mindful of the unit of measurement(s) used. Provide your analysis by comparing this result with the "Timing" result of the 100 cm data. 3. An ocean vessel using sonar sends a sound wave to the bottom of the sea and receives an echo after 0.3 sec. Assume a speed of sound in water to be 1480 m/s. Calculate the depth of the sea.

4. A ship sends an ultrasound to the bottom of the ocean floor at 2,618 m from the surface. The ultrasound speed in water is about 1531 m/s. Calculate the time taken by the sound waves to get reflected to the surface. 5. Whenever a wave is used as a probe (e.g. ultrasound), it is difficult to detect target details that is smaller than the wave's wavelength, 1. Higher frequency ultrasound would allow greater detail, but it lessen the penetration depth compared to lower frequencies. The acceptable effective scan depth is about 5002 into a tissue. (A) Calculate the minimum frequency of ultrasound that will allow you to see details as small as 0.250 mm in human tissue given the speed of sound in tissue is about 1540 m/s. (B) What is the effective depth to which this sound is effective as a diagnostic probe? Review: 1 = where v: speed of sound in a medium, f: frequency