The Plan… 8 April 2013 Begin Chapter 4 – Optics  4.1 Properties of Waves  PowerPoint, Handout, & Reading Check Parent Teacher Interviews Tomorrow…  I will give you a marks sheet, you take home, get signature = assigned work credit – DUE TOMORROW!!!  Your recent tests (re-tests & new) will be on it…  Blank score = still have time to do  Zero = zero (time limit to hand in = past)  n/a = you have been excused from task (c) McGraw Hill Ryerson 2007

4.1 Properties of Waves A wave is a disturbance or movement that transfers energy through matter or space. Examples?  Examples of waves include: water waves, sound waves, and microwaves. Energy is the capacity to apply a force over a distance. A force is a push or a pull on an object. See page 134

(c) McGraw Hill Ryerson 2007 Features of a Wave A crest is the highest point on a wave. A trough is the lowest point on a wave. The wavelength is the distance, in metres, for one complete cycle of the wave.  Crest to crest or trough to trough. The amplitude is the height of a wave crest or depth of a trough, as measured from its rest position. See pages Identify each of the lettered parts of the wave. Crest Trough Wavelength Amplitude

(c) McGraw Hill Ryerson 2007 Two Types of Waves The matter that waves travel through is called a medium.  I.e. Waves & Water, Sound & Air  Some waves such as light waves, can travel through space where there is no medium. Two types of waves that travel through a medium are:  Transverse wave – matter in the medium moves perpendicular to direction of the wave.  Compression wave – matter in the medium moves parallel to direction of the wave. See page 137 Transverse wave Compression wave

Transverse & Compression Waves “Up and Down” Waves = Transverse Waves I.e. When two people hold both ends of a skipping rope and wave it up and down… Sound Waves = Compression Waves or a Slinky… (c) McGraw Hill Ryerson 2007

Frequency See page 136 Frequency is the number of repetitive motions, or oscillations, that occur in a given time. Frequency is usually measured in hertz (Hz). When the frequency of a wave increases the wavelength decreases. What increased frequency here?

(c) McGraw Hill Ryerson 2007 Frequency Equation See page 138 Frequency can be calculated using the following equation: frequency = cycles/seconds (that’s cycles seconds) Use the above equation to find the frequency for each of the following: a) A hummingbird flaps its wings 120 times in 3 seconds. b) A DVD spins 35 times in 7 seconds. 40 Hz 5 Hz

Now what? Do the worksheets I gave you…  We’ll discuss tomorrow Reading Check P. 138  I have an idea:  Create a section in your notes, call it “Reading Checks”  Setup a section for each part of text: i.e. “Section 4.1 Properties of Waves”, next 4.2, and so on…  Write out the question from text, then write the answer…  What do you have?  STUDY NOTES for tests and final! You’re welcome Tomorrow: Activity 4.3 P. 139 & CYU P. 143 (c) McGraw Hill Ryerson 2007 If you need to write a test… SEE ME HASTA PRONTO!