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Waves & Energy

Waves & Energy. Vocabulary. Energy Wave Amplitude Conduction Convection Radiation Color spectrum Wavelength Potential energy Kinetic energy Light energy Chemical energy Mechanical energy. What is Energy?. “Energy” is defined as the ability to do work

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Waves & Energy

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  1. Waves & Energy

  2. Vocabulary • Energy • Wave • Amplitude • Conduction • Convection • Radiation • Color spectrum • Wavelength • Potential energy • Kinetic energy • Light energy • Chemical energy • Mechanical energy

  3. What is Energy? • “Energy” is defined as the ability to do work • Work is using energy to move something

  4. What are Waves? • A wave is a disturbance that transfers energy from place to place. • Most waves need a “medium” or substance to travel through • Glass, liquids & solids can all be mediums • Moving objects have energy. • A moving object can transfer energy to a medium, producing waves.

  5. Mechanical Waves • Waves that REQUIRE a medium through which to travel are called “mechanical waves.” • Mechanical waves do not carry the medium they travel through with them • Waves on the ocean do not move the water molecules with them • Molecules stay in place, just “bob” up and down transferring the energy onward • Mechanical waves are produced when an energy source causes a medium to vibrate

  6. Types of Waves • Mechanical waves are classified by how they move through a medium. • Two types of Mechanical Waves • Transverse waves • Longitudinal waves

  7. Transverse Waves • Transverse waves move the medium at a right angle to the direction of the wave • Moving a rope up and down, crests & troughs

  8. Longitudinal Waves • Longitudinal waves move the medium parallel to the direction in which the waves travel • Like a slinky being “pushed” back and forth • Compressions: when the coils or waves are close together • Rarefactions: when the coils or waves are farther apart. • Example: Sound

  9. Properties of Waves Foldable • Fold your paper into 4 sections • Label sections speed, amplitude, frequency, and wavelength • In each section write: • Definition • How you measure it in longitudinal and transverse waves • 3 facts • On the back, draw and label an example of each wave

  10. Waves • Wavelength • Amplitude • Frequency • Speed • The energy of a wave depends on the wavelength

  11. Wavelength • A wave travels a certain distance before it starts to repeat its motion • The distance between two corresponding parts of a wave • Crest to crest • Trough to trough

  12. Amplitude • Amplitude is the rise of a wave from the rest position • The more energy a wave has, the greater the amplitude. • It takes more energy to make a higher or greater amplitude. Rest position

  13. Amplitude • Amplitude of transverse waves: the maximum distance a wave moves up or down • Amplitude of longitudinal waves: measurement of how compressed or rarefied the waves are. • Dense compressions means it has a large amplitude

  14. Frequency • Number of complete waves that pass a given point in a certain amount of time. • If one wave passes by every second, the frequency is 1 wave per second. • Frequency is measured in hertz (Hz) • 1 Hz

  15. Speed • Light waves travel faster than sound waves (about a million times faster!) • Speed = how far the wave travels in a given length of time • Speed = distance/time

  16. Related Formulas • Speed, wavelength and frequency are related to one another • Speed = Wavelength X frequency • Frequency = Speed/Wavelength • Wavelength = Speed/Frequency • If you know two of the variables, you can solve for the other • If you increase the frequency, the wavelength decreases

  17. Practice • Complete the practice “Wave Math” worksheet for homework!

  18. What are Waves? • Waves that do not require a medium to travel are called “electromagnetic waves” • Light from the sun

  19. Electromagnetic Waves • Transverse wave that transfers electrical and magnetic energy • Moves at the speed of light (186,000 miles per second) • Do not require a medium, so they can travel through empty space, like space (vacuum)

  20. Electromagnetic Spectrum • All electromagnetic waves travel at the same speed, but they have different wavelengths and frequencies. • The electromagnetic spectrum is the complete range of electromagnetic waves in order of increasing frequency

  21. Electromagnetic Spectrum • Made up of: • Radio waves-radio, tv, microwaves • Infrared rays-heat lamps, infrared cameras • Visible light-colors, light we see • Ultraviolet rays-rays from the sun • X-rays-medicine, engineering • Gamma rays-some radioactive materials

  22. Electromagnetic Project • Draw and label the Electromagnetic Spectrum. • Follow the example I show. • Use page O74.

  23. Waves Mini-Lab • Needed materials: string, water, container, dropper, • Create an example of a transverse wave with string • Using pages O 24, follow the lab instructions. Answer the analysis questions. On pg 24 do not answer question 6. Write & fill in the table.

  24. Worksheet • Complete the worksheet “Properties of Waves” • You may use your notes, not your neighbor! • Complete the worksheet “Interactions of Waves”. Use book pages O 17-23.

  25. Properties of Waves • Complete the worksheet “Waves & Energy” • You may use your book or notes as a reference if necessary.

  26. Waves Reading & Worksheet • Read pages O 17-26. Use the worksheet provided as a guide to your reading • Complete the worksheet “Interactions of Waves”

  27. Waves Do need a ________ to travel through. Electromagnetic Transverse Waves _____ waves. Don’t need a ________to travel through. Lowest parts called ________. Spread-out parts called ______. Highest parts called ____. Examples of EM waves: (pg O 74) Close-together parts called ___.

  28. Lab • Tuning Forks, from the book manual.

  29. ENERGY! • List types of energy: • Light • Sound • Earthquake waves • Heat • Wind? • Electrical • Chemical • Nuclear • Energy is the ability to do work or cause change • When an object is moved because of energy, the energy is transferred to the object • Energy is measured in JOULES (J)

  30. Energy • Three mini-labs to complete with observations • 1.Compare the transfer of energy through various mediums • Sound • Light • Heat • Earthquake waves

  31. Heat • Heat is thermal energy moving from a warmer object to a cooler object. The energy depends on the movement of the atoms…lots of movement = higher heat • Does temperature rise at the same rate for everything? • Hot sand & cold water. • Specific Heat: amount of heat needed to increase the temperature but the temperature does not increase at the same rate for everything • How is heat transferred?

  32. How is heat transferred? • Conduction: heat is transferred from one object to another without the movement of matter. • Examples? • Convection: heat is transferred by the movement of currents within a fluid. • Examples? • Radiation: transfer of energy by electromagnetic waves • Examples?

  33. Heat Transfer Mini-Lab • Compare the transfer of heat by conduction, convection & radiation. Provide examples of each

  34. Light Energy, AKA Electromagnetic • Can transfer energy without a medium • Transverse wave that transfers electrical and magnetic energy through vibration • Light behaves like waves and packets at the same time • Electromagnetic waves have the same speed in a vacuum but have different wavelengths and frequencies • The amount of energy carried by an EM wave increases with frequency • EM spectrum made up of radio waves, microwaves, infrared waves, visible light, Ultraviolet waves, X-rays, Gamma rays. See page O 75

  35. Light Energy Mini-Lab • Demonstrate how white light can be separated into the visible color spectrum. • As light passes through a prism, the waves are “bent” or refracted • Red wavelengths bend the least • Complete five different observations with the prisms. For each, draw (using the colored pencils) the way you see the light separated. Use each of the light sources and try at least two different prisms.

  36. Potential & Kinetic Energy • Kinetic Energy: The energy an object has due to its motion • What can effect kinetic energy? • Velocity – has a greater impact on effecting the overall K.E. • Mass – more mass means more “E” to make it move • K.E. = ½ X Mass X Velocity ^2 • Potential Energy: stored energy that results from the position or shape of an object • Gravitational, elastic

  37. Potential & Kinetic Energy • Mechanical energy is the combination of kinetic and potential energy • Let’s talk PENDULUM: draw a picture, label potential and kinetic • Let’s talk bouncing ball • Are these examples “cyclic”

  38. Conversion of Energy • Most forms of energy can be transformed into another type of energy • Mechanical (movement) to electrical, such as a dam • Toaster: • Electrical to heat • Cell phone: • Electrical to electromagnetic • Your body: • Chemical to mechanical, Chemical to thermal

  39. Response to Energy • Plant to sunlight? • Humans to light, sound, motion • Cockroaches to light intensity • Name some devices that help people sense types of energy: i.e., seismograph

  40. Review • Section “M”’ • Page 201- 202: 1, 3, 5-9, 11-15, 19, 23 • Section “O” • Page 31: 1-7 • Page 32: 9-11, 13, 19 • Page 33: 1, 2, 3, 5, 6 • Page 101: 1, 2, 3, 7 • Page 102: 11, 13, 14, 15 • Page 103: 1, 2, 3, 4, 6

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