1. 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 24.1 - The Electromagnetic Spectrum

2. 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. 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. 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 10 14 Hz

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7. 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. 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

9. 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

10. 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

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12. 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: