1 PHYSICS Mr. BALDWIN WAVES 12-Feb-14 AIM: What is light? What is the electromagnetic (E-M) spectrum? DO NOW: What are the colors of the rainbow? Why are they different? How is it that heat comes to us from the Sun? Homework: Worksheet The Electromagnetic Spectrum

2 Electromagnetic Waves The electromagnetic spectrum consists of all types of electromagnetic radiation Gamma rays, x-rays, ultraviolet radiation, visible light, infrared radiation, millimeter waves, microwaves, and radio waves are all electromagnetic waves that differ only in their frequencies & wavelengths. ALL Electromagnetic waves travel in a vacuum with the same speed of light. (300,000,000 m/s) Write this in scientific notation.

3 Electromagnetic Spectrum Infrared radiation (IR) – created by molecular vibrations Visible light (white light) – created by electron excitation Ultraviolet radiation (UV) – created by electron excitation X-ray radiation – created by high energy electron excitation Gamma (γ) radiation – created within the atomic nuclei by high energy nuclear processes Ionization Radiation is any radiation that is energetic enough to ionize biological matter. – Causes genetic mutation of DNA – Penetrate deep into matter As λ decreases, the f increases, and hence the energy E increases

4 Components of Visible Light White light is polychromatic: – Made up of different colors of light – RedOrangeYellowGreenBlueIndgoViolet Wavelength Range of visible light  400 – 700 nm (Nanometer: 1nm = 10 –9 m Write these values in scientific notation in meters Determine the Frequency Range of visible light f: 4.3 – 7.5 x Hz

5

6

BALDWIN7 PHYSICS Mr. BALDWIN GEOMETRIC OPTICS 13-Feb-14 AIM: How does light behave when it is incident on another medium? DO NOW: Write a short paragraph on what you observe when a pencil or spoon is placed in a clear glass of water. HOME WORK – Read up on Geometric Optics 7

8 Reflection; Refraction Reflection: the return or change in direction of a wave (light or sound) at the same angle is called reflection – Echo is sound reflected Refraction: the change in direction and speed of a wave as it passes from one medium to another – Bending of light as it passes through a prism

Reflection: Law of Reflection Law of reflection: the angle of reflection (that the ray makes with the normal to a surface) equals the angle of incidence. 9

Refraction: Snell’s Law This is called Refraction. angle of refraction Light changes direction (bends) when crossing a boundary from one medium to another. This is called Refraction. The angle the outgoing ray makes with the normal is called the angle of refraction. 10

11

12 index of refraction Light slows when traveling through a medium. The index of refraction of the medium is the ratio of the speed of light in vacuum to the speed of light in the medium: