Waves Unit Study Guide – Flashcards
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1. What is a wave?
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A wave is a disturbance that transfers energy.
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2. What cause waves?
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Forces cause waves by starting disturbance.
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3. What do waves transfer?
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All waves transfer energy.
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4. Waves can be categorized based on how they move. Name them.
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1. Longitudinal Waves 2. Transverse Waves
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5. Describe how longitudinal waves travel.
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In longitudinal wave, waves travel in the same (or parallel) direction as the disturbance.
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6. Describe how transverse waves travel.
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In transverse waves, waves travel in the perpendicular direction as the disturbance.
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9. What is medium?
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A medium is any substance (matter) that a wave move through.
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10. You can hear the voice of your best friend. What is the medium for sound waves?
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Air
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11. Your ground is shaking during an earthquake. What is the medium for seismic waves?
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Ground
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12. What are mechanical waves?
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Mechanical waves transfer energy through matter (medium).
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13. What would happen to mechanical waves without medium?
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There would be no mechanical waves. No ocean waves with ocean water. No sound waves without air. No seismic waves without ground. No rope waves without a rope.
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14. What kind of energy is transferred by mechanical waves?
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Kinetic Energy (Energy of Motion)
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15. Why doesn't a floating boat move with ocean waves?
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Because waves only transfer energy, not matter (boat and water molecules).
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16. When someone screams at you, do air molecules move toward you?
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No. Sound waves only transfer energy not matter (air molecules).
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17. What is not a mechanical wave?
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Light (or electromagnetic waves)
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18. Why is light not a mechanical wave?
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Light waves can transfer energy through empty space (without medium).
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19. What are measurable properties of waves?
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1. Amplitude 2. Wavelength 3. Frequency 4. Speed
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22. How do you measure wavelength?
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Distance between crest to crest or trough to trough.
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23. How do you measure amplitude?
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Distance from the midpoint to the crest (or trough) of the wave.
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24. What does amplitude tell us about a wave?
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Wave's amplitude indicates how much energy a wave is carrying. The bigger the amplitude, the more energy the wave has.
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25. Why is tsunami more dangerous than typical ocean waves?
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Tsunami is much bigger wave due to its large amplitude (more energy).
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26. How do you measure frequency?
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Count the number of crests (or troughs) that pass by a given point in one second.
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28. Frequency is measured in Hertz (Hz). What does 100 Hz mean?
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100 Hz (100 waves per second) means that for every one second 100 waves pass by a given point.
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29. How are frequency and wavelength related?
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-Frequency and wavelength have inverse relationship. -High frequency waves have shorter wavelength. -Low frequency waves have longer wavelength.
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30. What two information do you need to find wave's speed?
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1. Wavelength 2. Frequency
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31. An ocean wave has the wavelength of 4 meters and the frequency of 0.5 Hz. What is the speed of the ocean wave?
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Speed is 2 m/s. You multiply 4 meters by 0.5 Hz which equals 2 m/s
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32. Two singers are singing at different frequencies: 1000 Hz and 2000 Hz. Whose wavelength would be longer?
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1000 Hz sound will have longer wavelength because frequency and wavelength have inverse relationship.
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34. In which medium do sound waves travel fastest? Slowest?
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Sound waves travel fastest in solids. Then liquids. They are slowest in gases.
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35. If ocean waves have a speed of 20 m/s and frequency of 5 Hz, what are their wavelength?
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Divide speed by frequency to find the wavelength. The wavelength is 4 m.
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36. Waves can interact with matter and be...
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All waves, both mechanical and light waves, can be 1. Absorbed 2. Reflected 3. Transmited
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37. Explain transmission of a wave.
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Transmission describes when waves pass through a medium.
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38. Explain absorption of a wave.
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Absorption describes when waves disappears in a medium.
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39. Explain reflection of a wave.
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Reflection describes when waves bounce off a medium.
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40. Describe transparent materials.
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Transparent materials allow most of the light to pass straight through. You can see images through them.
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41. Describe translucent materials.
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Translucent materials transmit some light and but the image appears blurry.
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42. Describe opaque materials.
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Opaque materials do not allow any light to pass through. You cannot see any image through them.
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43. Radio wave is an example of...
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Radio wave is an example of light (electromagnetic) wave.
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44. Seismic wave is an example of...
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Seismic wave is created when earthquake occurs. It's an example of mechanical wave.
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45. What happens to wave's speed when it moves from one medium to another? Assume these mediums are different.
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Wave's speed will change.
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46. Think about our wave machine made of candies. What happened to the wave speed when the wave moved from light candies to heavier candies?
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The wave slowed down moving from light medium (candies) to heavier medium (candies).
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47. A long rope is made of two type of materials. One half is made of light material and the other half is made of much heavier material. Describe the rope waves generated from the lighter end.
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As waves move from lighter material to the heavier materials, their speed will decrease.
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48. A glass is made of materials capable of absorbing blue and yellow light. Which light will be visible on the other side? (look at the picture)
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On the other side of the glass, you should see red and green lights.
