1. Light

2. LIGHT Light is a kind of energy that travels in waves. Light can also behave like individual packets of energy – called photons. Light can pass through some things, but not others.

3. LIGHT Light travels very fast and in straight lines.

4. Absorption, Reflection, and Transmission Light coming in – incident light

5. Reflection Reflection: light that bounces off an object.

6. Transmission Transmittance – light that passes through an object

7. Absorption Absorption – light that enters an object and is not reflected or transmitted

8. Absorption, Reflection, and Transmission Which forms of light cast a shadow? Can an invisible person cast a shadow?

9. Reflected Light An image can bounce back off an object, such as, a mirror, pond or lake, or shiny metal.

10. What happens to Absorbed Light?

11. Light is the kinetic energy of moving photons Reflected light does not enter the white block. Most of its kinetic energy is reflected as well

12. What happens to Absorbed Light? Light energy that is absorbed by the dark block is transferred to the molecules in the block, causing them to move faster. Heat is therefore produced and radiates from the block.

13. Spectrophotometer

15. Concentration Concentration = mass of solute/volume of solvent Units can be g/L or g/mL The more solute dissolved, the more concentrated the solution.

16. Concentration Curve Estimate the Concentration of these samples AbsorbanceEstimated Concentration (g/mL) 0.30____________________ 0.45____________________ 0.75____________________

17. Light and Energy The Sun, ultimate source of most energy on Earth Surface = 5,600°C Center = 15,000,000°C 75% Hydrogen 25% Helium

18. Nuclear Fusion Nuclear fusion: Occurs at very high temperature and pressure Nuclei of 4 hydrogen atoms fuse together Form helium atom and photon

19. Light and Energy One helium atom weighs slightly less than 4 hydrogen atoms The Law of Conservation of Matter states that matter can neither be created of destroyed Einstein concluded that this loss of matter was converted to energy in the form of a photon Matter and energy are related to each other according to Einstein’s formula: E = mc 2 (energy = mass x speed of light 2 )

20. Resistance in an Incandescent Light Bulb Produces Photon Tungsten filament in a light bulb is very thin and about 2 m long Electrons struggle to pass through the long, thin filament = resistance Filament heats to about 2,200 ° C This causes the wire to glow and give off light as photons

21. Law of Reflection Angle of Incidence: The angle at which light hits an object Angle of Reflection: The angle at which light is reflected off an object Law of Reflection: the angle at which light hits an object is equal to the angle at which light is reflected from the object (  A =  B)

22. Mirrors When you look into a mirror, you see a virtual image of the real image reflected in the mirror. It appears the same size and distance from the mirror as the real image. It therefore appears that you are “looking into” the mirror.

23. Angles of Incidence and Reflection Determine the angles of incidence and reflection.