Unit 8: Optics lesson 1: Electromagnetic radiation

What waves make up the electromagnetic spectrum? 10 min – point of emphasis: visible light is only a small portion! (microwaves)

All waves in the electromagnetic spectrum travel at the speed of light. = 3.0 x108 m/s Example: Find the wavelength of each radio station. “Rock-101” (101 MHz) AM-600 (600 kHz) 10 min c f 3.0 x 108 a) c = f  so  = = = 3.0 m 101 x 106 c f 3.0 x 108 b) c = f  so  = = = 500 m 600 x 103

Brain Break!

What Causes Electromagnetic Radiation? Changing magnetic fields cause electric fields (this is how generators work). Changing electric fields cause magnetic fields (this is how electromagnets work). Vibrating electrons cause changing electric fields which cause changing magnetic fields… e- Vibrating electron 10 min Magnetic field electric field Note: the wave of radiation travels in a straight line!

Law of reflection: өi = өr өi : angle of incidence not shiny өi өr normal line (90) 10 min өi : angle of incidence өr : angle of reflection shiny

Quick Review: Pg. 210 #4 and 6 10 min

Unit 8: Optics lesson 2: images

Properties of an Image Size: larger, smaller, or the same compared to looking directly at the object? Location: where does the image appear to be compared to the object? Type: real (the rays converge and the image can be projected onto a screen) or virtual (the rays do not converge and the image cannot be projected onto a screen)? Attitude: upright or inverted (upside-down)? 15 min

Image in a Plane (flat) Mirror 10 min Image Characteristics: size – location – type – attitude – same opposite (behind mirror) virtual (the rays do not converge) upright (laterally inverted)

Brain Break!

Pinhole camera ho hi do di Simplest and oldest type of camera. hi di 10 min hi ho di do Image Characteristics: size (hi) – location – type – attitude – smaller M = = closer real (rays converge) inverted M = magnification

Try This: A pinhole camera 300 mm long forms an image of a 180 cm tall man 4.5 m away. Find the size and other characteristics of the image. hi/ho = di/do hi = (di/do) x ho = (30/450)x180 = 12 cm 10 min location – type – attitude – closer real (rays converge) inverted