1. Warm - Up  1. How was Spring Break? What did you do?  2. The School store uses a new pricing system. A vest costs $20, socks: $25, a tie: $15 and a blouse costs $30. Under this system, how much would a pair of underwear cost?

2. Electromagnetic Radiation (EM Waves)

3. Faraday and Ampere’s Laws  Electricity and magnetism operate via ‘fields’  Ampere-Maxwell law: A changing Electric field creates a Magnetic field  Faraday’s Law: A changing Magnetic field creates an Electric field  The created field is perpendicular to the original field.

4. How are EM Waves created

5. Ways to create EM Radiation  Moving Charges Why we need antennae  Sources of radiation Microwaves Radio Antennae Stars X-Ray Machines

6. Uses?

8. Properties

9. Standard wave properties  Amplitude  Wavelength  Frequency

10. Light Speed  The speed of light is a universal constant,  It is independent of the frame of reference.  299,792,458 m/s (in a vacuum) Found experimentally confirmed mathmatically  3 * 10 8 m/s is good enough  Written as ‘c’

11. Electromagnetic spectrum All travel at the same speed but, EM waves are differentiated by wavelength, frequency, energy

13. Flux  Rate at which light is emitted from a source (measured in lumens [lm])  Illuminance – illumination of a surface (lm/m 2 = lux)

14. Illumination  Inverse square relationship  Double the distance from a light source, and you decrease by ¼ the illumination

15. Particle nature of light  The wave model of light fails when we shine light on zinc, which causes a release of photoelectrons.  Increasing the intensity of the light does not always cause more electrons to be released,  Emission depends on frequency (color)

16. Photo electric effect  Einstein thought light could be quantized  Called light quanta: photons Photon energy depends on the frequency of the photon E = h * f  h = Planck’s Constant = 6.6 x 10 -34 J s  F = frequency

17. Work 16.1 – Pg 389  P389  (1-4, 7, 10-12, 16, 20,21, 31-33, 41)

18. Homework  Draw an EM spectrum  Need to have: Wavelength (units labeled), type of wave, frequency, examples drawn and labeled, also which end is low energy, which is high.  See P 374