Nature of waves

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Grade 7 lesson about the nature of waves

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Nature of waves

  1. 1. Nature of Waves By: Victor R. Oribe
  2. 2. A Vibration is a repeated back andforth motion or oscillation of anobject.
  3. 3. Any elastic solid can be made tovibrate. Amplitude is the maximum displacement an elastic object can make. When the load is released, it vibrate back and forth.If the surface is frictionless, then the magnitude of themaximum displacement to the right and to the left of theequilibrium position are equal
  4. 4. The motion of the load repeats itself over and over on a definite path in equal intervals of time.The periodic vibration of the mass is called SimpleHarmonic Motion (SMH).SMH is a type of vibration along a path in which thedisplacement of the object from its equilibrium position isalways equal above and below its equilibrium position
  5. 5. A simple pendulum oscillates back and forth. If the pendulum bob moves from A to C then back to A, it has one complete vibration. The time it takes the pendulum bob to complete one vibration is called the Period or T. The number of complete vibration in a second is the Frequency or f.
  6. 6. Assignment:1. In your own words, explain the following: 1. vibration 2. elastic object 3. period 4. frequency 5. amplitude 6. simple harmonic motion 7. equilibrium position2. Explain how waves are produced.
  7. 7. Vibrating objects act as sources of different forms of waves.Vibrating Radio waveselectronsEarthquake beneath Radio waves the ocean
  8. 8. Electromagnetic Waves Waves that need no medium to travel in.James Clerk Maxwell a Scottish physicist predicted theexistence of electromagnetic waves in 1865.Maxwell found out that these waves are produced byoscillating charges.Examples of these waves are: a. light waves b. radio waves c. microwaves d. X-rays
  9. 9. Mechanical WavesWaves that need materials medium through which theycan travel.Some examples of mechanical waves are sound wavesand water waves, or a waves that travel along a spring orrope.
  10. 10. For the waves in a string, the particles oscillates up anddown while the waves move horizontally.The direction of motion of the particles of the medium(string) is perpendicular to the direction of thewaves, these waves are called Transverse Waves.
  11. 11. When the end of the spring is pushed and pulled,a series of compressions and expansions occur. compressions expansions
  12. 12. Compressions and expansions are equivalent to the crestand troughs of a transverse wave.compressions expansions
  13. 13. Waves in Different MediaTransverse waves travel through a medium whoseparticles are attached to one another.Gas particles are widely separated making transversewaves unable to travel through them.A longitudinal waves causes particles of a gas to movecloser together or farther apart, making gas a mediumfor it.Both transverse wave and longitudinal waves can travelthrough a solid since the particles of solid can vibrateabout their relatively fixed positions in any directions.
  14. 14. Guide Questions:1. Differentiate electromagnetic waves from Mechanicalwaves.2. What are the different types of mechanical waves?3. Compare and contrast longitudinal and transversewave in terms of: a. direction of oscillation of the particles b. direction of motion of the waves c. medium through which they can travel
  15. 15. Wave Characteristics
  16. 16. Crest is the high points on a wave.Troughs is the low points on wave. Amplitude is the distance of the crest or trough from the midpoint of the waves. Wavelength is the distance from crest to crest or trough to trough
  17. 17. Frequency (f) refers to the number of crests or wavesthat pass a fixed point per second measured in hertz(Hz)
  18. 18. Set workIdentify the different part (characteristics) of waves.
  19. 19. Assignment1. Give at least five examples on how energyis transmitted by waves.2. Give at least five reasons how energy istransmitted by waves.
  20. 20. Research Work1. Make a research on how microwave oven operates.2. Is it safe to use microwaves oven?
  21. 21. Short Quiz1. Answer the chapter quiz (Chapter 16).2. Copy and answer.

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