"Waves" REVISION 8F1

Please write your FULL name Introduction to waves (REVISION) When waves move through a medium, the waves formed may be longitudinal waves or transverse waves. Term Defintion frequency Refers to number of waves passing a given point in aperiod of time amplitude Maximum displacement of vibrating particles in the medium medium Refers to air, water, etc. that waves move through crest Refers to the high point of a wave trough Refers to maximum downward motion by a particle in awave transverse Wave where motion of particles in medium is up anddown longitudinal Wave where motion of particles in medium is horizontal wavelength Distance between two consecutive corresponding points in the wave amplitude Distance from center of wave to point of greatest displacement particles The movement of these differ in longitudinal and transversewaves. WAVE SPEEDIt is important to note that all waves move at specific speeds. Waves move at different speeds depending on the mediums through which they are moving. For example, a wave moving through water moves at a different speed than a wave moving through air. The speed of a wave depends on the length of the wave and the frequency (number) of waves passing a given point in one second. On the diagram below, the wavelength from "a" to "b" is two meters. In the diagram, each wave is labeled "a", "b", and so on and numbered w1, w2, and so on.Assume you are standing on a dock and watching the waves pass directly below where you are standing. You count the number of seconds it takes for w1, w2, w3, and w4 to pass directly below you. You determine that all four waves pass below you in two seconds. In the picture above, the total time it takes waves w1 - w4 to pass you is two seconds. That means that the first wave only takes _ second(s) to pass you 1 2 1 1 Each wavelength is _ meters. 1 2 3 4 Every second, _ wave(s) pass below me. 1 2 3 4 The _ of waves passing below me is two per second. amplitude wavelength crests frequency The formula for finding the speed of a wave is: Speed= frequency*wavelength or s= f*wlIn the formula, frequency is the same as the _ of waves passing below where you are standing on the dock. number size In the picture above, we now know the the frequency of the waves are two waves per second and the length of each wave is two meters. The speed of the wave is found by multiplying the frequency by the length of the wave. What is the speed of the wave? 2 m 4 m 1 m not enough information is provided. A certain FM radio station broadcasts electromagnetic waves at a frequency of 90,500,000 Hz. These radio waves travel at a speed of 300,000,000 m What is the wavelength of these radio waves? 3.31 m A dog whistle is designed to produce a sound with a frequency beyond that which can be heard by humans (between 20 000 Hz and 27 000 Hz). If a particular whistle produces a sound with a frequency of 25,000 Hz, what is the sound’s wavelength? Assume the speed of sound in air is 331 m 0.013 m The lowest pitch that the average human can hear has a frequency of 20.0 Hz. If sound with this frequency travels through air with a speed of 331 m what is its wavelength? 16.6 m A 10.0 m wire is hung from a high ceiling and held tightly below by a large mass. Standing waves are created in the wire by air currents that pass over the wire, setting it in motion. If the speed of the standing wave is 335 m and its frequency is 67 Hz, what is its wavelength? 5 m Sonar is a device that uses reflected sound waves to measure underwater depths. If a sonar signal has a frequency of 288 Hz and the speed of sound in water is 1,450 m what is the wavelength of the sonar signal? 5.03 m