Welcome back! 4-8-13 Reminders: The last Wednesday of class was a lab activity. We are now in a new marking period. The gradebook will be up to date within 24hrs. We finished Chapter 27 (light) and will now begin Chapter 28 (color) and quickly move on to Chapters 29-31 (reflection, refraction, lenses, etc.). Today's Learning Objective: Identify the different regions of the EM spectrum and compare in terms of wavelength, frequency, and energy.

Warm up: EM Spectrum and light

Video recap: We are always bombarded with the various EM waves. How do they interact with the atoms of other objects? How do we block the various EM waves (ex: color)? Which waves do we use for different purposes? How do the waves properties of wavelength, frequency, and energy/power relate? How do scientists use various EM waves to study different aspects of the universe, both big and small?

Radio Telescopes Used on earth and in space to "view" things very far away or across a large distance.

Where do gamma waves come from?

Gamma waves are the most powerful and most harmful (highest frequency).

Where are people's exposure to gamma rays greatest?

Have you ever been to Las Vegas? It may be more hazardous to your health than you think; It is an environmentalist's nightmare!

Hoover Dam

Papers passed back: Please file them into your portfolio. Portfolios haven't been collected in a while, but will be collected at the time of the next test. Review the assignments; if you have any questions about an assignment, please ask.

Pass back and review: Ch. 27 - Light questions pt. 1 1. Photon = a particle of light, a massless bundle of concentrated EM energy. 2. Light year = the distance (measured in km) that light can travel in one year's time. The distance is equivalent to roughly 9,461,000,000,000-km or 5,878,000,000,000 miles. 3. Speed of light = typically about 300,000-km/s through a vacuum such as space. 4. Source of all EM waves = accelerating electric charges, electrons in atoms.

5. The seven (7) main EM waves: radio, micro, infrared, light, UV, X-ray, gamma 6. EM spectrum with relative: wavelengths, frequencies, level of energies (see pg. 408) 7. All EM waves travel at the speed of light.

ROY G BIV

Today's assignment: 4-8-13 Complete and submit the Chapter 28 - Color Questions worksheet using the text. Be sure to put your name on your paper. Share the color pencils located by the windows. Today's Learning Objective: Identify the different regions of the EM spectrum and compare in terms of wavelength, frequency, and energy.