On the electric waves the sounds travel with the speed of light to a drum-head disc in the receiver held at the ear of your friend. Is it simply that when one person talks into his/her cup, the bottom of the cup vibrates back and forth with the sound waves and the vibrations travel through the string by pulling the string back and forth, therefore, the bottom of the second cup should start to vibrate back and forth just like the bottom of the first cup is vibrating, producing sound waves. The cup transferred the vibration into the air, which we could then hear.). wave in the string sound wave in air A) The wave is transverse.yes yes B) The wave speed increases. 3 - If a string of a violin or a harp vibrates back and forth, it is compressing and expanding the surrounding air, thus producing a sound. ... A standing wave is set up in a string of variable length and tension by a vibrator of variable frequency. So, why does a standing wave happen and how does it happen? These vibrations are transmitted along the medium and then reconverted back to sound. Sound travels through the air but it travels even better through solids such as your cup and string, allowing you to hear sounds that … We are going to model a simple string guitar, analyze how sound moves through our model, and think about how the model relates to a telephone. Each of these vibration patterns is called a mode. Explain the procedures to the students before passing out the materials. 3. 2. Experiment with your string telephone by gently pulling the string taut and then letting it fall loose. If someone grabs the string, or it gets stuck on something, the sound waves dissipate, and the phone … MCQ Questions for Class 9 Science Chapter 12 Sound with Answers MCQs from Class 9 Science Chapter 12 – Sound are provided here to help students prepare for their upcoming Science exam. Short string lengths keep sound vibrations from losing noticeable energy. Assume the sound waves travel to the listener without being disturbed. (Answer: The vibration, or sound wave, from my finger traveled along the string and into the cup. When a string or wire is stretched tightly between two posts and then plucked, it will vibrate according to the length of the string. Use a long piece of string to help the sound travel farther. Md. off the vibration or letting the string go limp, the sound will usually travel well. A pulse is sent down the string. The amplitude of a sound wave decreases with distance from its source, because the energy of the wave is spread over a larger and larger area. For this string though, we're making sure that there have to be nodes at each end. That wave would travel through the air at the speed of sound in the air, which is about 350 m/s, and it would have a very long wavelength in the air of about 350/.5= 700m. Take one minute to discuss with the people around you what is happening. Stand away from each other so the string is taut. A sound source emitting sound with a frequency of 400 Hz is placed at the entrance of a tube that is attached to a moving piston, as shown in FIGURE 3. Any reusable equipment that is necessary to teach the activity is not included in this estimate; see the Materials List/Supplies for details. You'll have learned about waves in your science lessons. Did you know that sound is a wave? If this happens attach the string to a small paper clip to anchor it in the cup. It did not just disappear. When a sine wave is used to represent a sound wave, the crest corresponds to: a. rarefaction b. condensation c. point where molecules vibrate at a right angle to the direction of wave travel d. region of low elasticity 2. The sound wave actually moves the tiny particles, or molecules, that make up the solid. Did you know that sound is a wave? WAVES AS MCQ 2000 to 2017 part 02 1. But some of the energy is also absorbed by objects, such as the eardrum in Figure 14.5, and some of the energy is converted to thermal energy in the air. What happened to the vibration you felt in your hand? WAVES PART 02 AS LEVEL PHYSICS P 1 DO IT WITH PASSION OR NOT AT ALL. A pulse is sent down the string. ), What happens when the vibrations (sound waves) reach the other end of the cup? (d) Determine the direction of propagation of the wave. Old landline phones were created using the same principle as a string telephone. Speed of a sound wave can also be affected by the density, temperature, and elasticity of the medium through which the sound waves travel. Although no charge or fee is required for using TeachEngineering curricular materials in your classroom, the lessons and activities often require material supplies. within type by subtype, then by grade, etc. Poll: During the introduction, ask students the following question. The waves then travel through the string, provided it is pulled tight enough and then make it to the second cup. Wave on a String simulator. (Answer: It left when I transferred my hand to the cup. These waves travel back and forth along the string but the resultant motion is a standing wave due to the addition of the left and right travelling components. Two-Way communication or letting the string telephone hand to the bottoms of two paper cups get! Lesson 2, string telephones for two-way communication this current comes from your moving finger and is. Should notice a difference, since sound waves materials acting as the medium that as! A medium, and what this shows about the way sound travels a... 1 do it with PASSION or not at all the only factor that affects a sound.... It happen consultant, author, speaker, and discuss as a class conform to this strict hierarchy a of. State of the hole in the air in the Middle supplies needed for each group of students in! 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