Waves & Energy

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 • Wavelength is the distance between two 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. 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)

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 increase the frequency, the wavelength decreases

17. Mini-Lab! • Station 1- Frequency • Station 2- Amplitude • Station 3- Speed • Station 4- Wavelength

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

19. Reflection • When a wave hits a surface through which it cannot pass, it bounces back.

20. Refraction • When a wave enters a new medium at an angle, one side of the wave changes speed before the other side causing the wave to bend.

21. Diffraction • When a wave moves around a barrier or through an opening, it bends and spreads out

22. Constructive Interference • Waves combine to make waves with a larger amplitude

23. Destructive Interference • When two waves combine to make a wave with a smaller amplitude.

24. Waves Lab • Needed materials: water, container, dropper, • Using pages O 24, follow the lab instructions. Answer the analysis questions. • Do not answer question 6. • Write & fill in the table.

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

26. 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)

27. 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

28. Light Energy, AKA Electromagnetic • Light behaves like waves and packets of energy at the same time • The amount of energy carried by an EM wave increases with frequency

29. 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

30. 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. Try at least two different prisms.

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

32. 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.

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

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

35. 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 ___.

36. 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)

37. 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

38. 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”

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

40. 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.

41. Specific Heat • Amount of heat needed to increase the temperature but the temperature does not increase at the same rate for everything

42. 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?

43. Heat Transfer Activity • Compare the transfer of heat by conduction, convection & radiation. Provide 3 examples of each.

44. 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

45. 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

46. 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