Lesson 1 What is light? Objective: see lesson Do Now Define Electric Field.

Electric and Magnetic Fields Electric Field – A thingy that exists in space that exerts force on electric charge Magnetic Field – A thingy that exists in space that exerts force on magnets Creating – Electric Field 1.Electric charge 2.Changing Magnetic Field – Magnetic Field 1.Electric current 2.Changing Electric Field

Light Animation /PlaneWave-2.html /PlaneWave-2.html Youtube animation

EM Waves Wave of magnetic and electric field which are perpendicular to each other. Traveling wave Types of EM waves – Different types differ only in freq (wavelength) Travel at:

Lesson 2 Light basics and ray optics Objective: see lesson Do Now What is the speed of light? Is this always the speed of light?

Light Basics Speed of light – In vacuum c = 3 x 10 8 m/s – In other things Slower than c Color  frequency changes with medium, freq does not P330

Ray optics Assume: – light made of VERY thin beams (called a ray!) – Rays travel in straight lines

Reflection Like with all waves, when medium changes – Some reflects, some goes through (transmits) Rough surface – (See p349) – Reflected beam has random angle Smooth surface – Angle of reflection = angle of incidence Angles relative to normal – (draw diagram on board)

Classwork A ray of light hits a VERTICAL smooth reflecting surface at and angle of incidence of 20 o. Draw a diagram which includes the surface, incident ray and reflected ray. Label angles. Devise a system for quantifying (putting a number on) roughness of a surface.

Discussion Why don’t you see your refection in a brick wall? Each ray comes off in a single direction. But, an image is made of many ray.

Objective: see lesson Do Now

Refraction Like with all waves, when medium changes – Some reflects, some goes through (transmits) If wave hits transition at angle, it bends or changes direction -- REFRACTION – (See p349) Which direction does it bend? See p349 – Fast to slow  towards normal – Slow to fast  away from normal Lesson 3 Snell’s Law

Snell’s Law vacuum: n=1 air: n= water: n=1.33 glass:n=1.5

Index of refraction and speed of light

Example Problem A ray of light traveling in air hits a block of glass at an angle of 30 o. The index of refraction in the glass is 1.5. Draw the reflected and refracted rays and label all angles. What is the speed of light in the glass?

Do This! A ray of light is traveling in glass (n=1.5) and hits an interface with air at an angle of o. Find the angle of refraction. Draw a diagram. What if the angle were larger than 41.8 o ? Lesson 4 Total Internal Reflections

Total Internal Reflection