A: PARTICLE-Energy of Light is contained in small packets. These bundles of energy are called photons. Explains why light can travel through space. Also explains “Photoelectric Effect” (Energy from a light shining on a metal plate gives electrons on the metal enough energy to escape. Bright light has more energy than dim light. But dim blue light can dislodge electrons while bright red light can not.) RAYS- Rays (arrows) are quick to draw and show the straight-line nature of light. WAVES- Mechanical; Needs medium Electromagnetic; No medium needed. LIGHT AS WAVE- We define it as a transverse, electromagnetic wave. Light reflects, diffracts, and refracts. PARTICLE DUALITY- So light is a wave AND a particle. It was theorized in 1905, and all work since then has confirmed that light sometimes behaves like particles and sometimes like waves. In 2014/2015, scientists in Switzerland were able to see light as BOTH … AT THE SAME TIME! And they got a picture of it! B: LIGHT MOVING- Velocity/Speed can change depending on the situation.Speed of light is a fundamental constant. c = 3 x 108 m/s (300,000,000 m/s). This can be substituted for v: c = d/t c = f???? ENERGY- A constant speed means as frequency increases, wavelength decreases. c = λ???? E = h???? h = Planck’s Constant

(6.626 x 10-34 Js)LOW ENERGY-Radio waves (micro) contain such small amounts of energy, usually not reported. New energy unit! Electron Volt (eV) 1 eV = 1.60218 x 10-19 j Even with new unit, low energy lights contain smaller than 1 meV (10-3 eV) MEDIUM ENERGY-(Microwaves) Infrared, Visible (Ultraviolet) Larger energy amounts, but still quite small 0.001 eV to 10 eV, (1.6 x 10-22 j to 1.6 x 10-18 j) HIGH ENERGY- (Ultraviolet) X-Rays and Gamma Rays Energies greater than 10 eV. This is known as ionizing radiation; there is literally enough energy to rip electrons from atoms and molecules! EFFECT OF MEDIUMS- Much like sound waves change in different mediums, so to does light! C: SUPERPOSITION OF LIGHT- Multiple waves interact with each other in superposition. Two waves in the same space will add together. Above equilibrium (crest) = positive Below equilibrium (trough) = negative. In reflection, diffraction, and refraction; it is the combination (superposition) of waves that results in what we see. REFLECTION- In reflection, diffraction, and refraction; it is the combination (superposition) of waves that results in what we see. DIFFRACTION- Waves hit a corner of a boundary and bend around. Diffraction is wavelength dependant! The longer the wavelength, the more diffraction. POLARIZATION- Related to diffraction;Works only because of the perpendicular nature of the electric and magnetic fields of light! REFRACTION- Waves hit a new medium and either speed up or slow down. SPEED OF LIGHT- We know that c = 3 x 108 m/s. This is a constant; it is also for light in a vacuum. MIRAGES- Waves can refract.

In this case the surfaces are the hot and cold air. QUIZ ANSWERS- 1. Light is a Transverse Electromagnetic  wave. 2. Gamma Rays most energetic. 3. Visible Light (Rainbow) have the same speed. 4. High energies also called ionizing radiation. 5. Gamma and X-Rays used in medicine. 6. Frequency of light increases, wavelength decreases. 7. Wavelength of light increases amount of energy decreases. 8. Distance affects the amount of energy an observer experiences from elect. Rad. , the smaller the distance between source and observer, the more energy is present. 9. Photoelectric effect- Energy from a light shining on a metal plate gives electrons in the metal enough energy to escape. Blue light is more energetic than red. This supports light is a particle. 10. Young’s Double Slit Experiment- When the light enters the box, the frequencies of the waves interfere w/each other causing a rainbow to show up. 1. Ocean is blue bc it reflects blue light. 2. Glare is bc of horizontal light waves, reduced by vertical polarized lenses. 3. Light travels slowest through solids. 4. A binary star system can be misinterpreted as a single star bc the lens has limited resolution. 5. The separation of white light into different colors by a prism is called dispersion. 6. Diffuse reflections occur when the reflecting surface is rough. 7. To block out 100% of light the two polarizing films would need to be perpedicular. 8. The moon is illuminous. 9. MIRAGES