You need a calculator today! Test Tomorrow – if you have missing work from this unit, it needs to be turned in tomorrow, or you get your free 40 percent forever!

understand the electromagnetic spectrum and how it is organized. 4. Complex Knowledge: demonstrations of learning that go aboveand above and beyond what was explicitly taught. 3. Knowledge: meeting the learning goals and expectations. 2. Foundational knowledge: simpler procedures, isolated details, vocabulary. 1. Limited knowledge: know very little details but working toward a higher level. understand the electromagnetic spectrum and how it is organized. understand what different types of electromagnetic radiation can reveal about astronomical objects. understand and describe important properties of electromagnetic radiation. understand how technology is used to collect electromagnetic radiation and turn it into images. understand what can be learned from analyzing the light from astronomical objects. understand how different types of telescopes work understand how lenses are used in telescopes.

2/17/2016 BellWork How are frequency, wavelength and energy related?

Question of the day How can you determine the temperature of a star when they are so far away?

The Color of Stars Blackbody radiation is the type of EM radiation emitted by a blackbody (an opaque and non-reflective body) held at constant, uniform temperature. Ie. Temperature determines color, so you can look at color to figure out temperature. The temperature of a lava flow can be estimated by observing its color. The result agrees well with measured temperatures of lava flows at about 1000 to 1200 °C.

The radiation (light) has a specific spectrum and intensity that depends only on the temperature of the body, and can be seen in a blackbody curve. http://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html

Read the FYI The color of stars

Create this…. Peak color Temperature (K) Wavelength Energy intensity Infrared Red Orange Yellow Green Blue Violet Ultraviolet

Wein’s Law Max λ = C_ T(K) C= constant = 0.29 cm K Mathematical formula that shows the relationship between temperature and color (wavelength) Max λ = C_ T(K) C= constant = 0.29 cm K T(K) = temperature in K λmax= maximum wavelength (color)

Calculate the wavelength. [Wein’s Law] Max λ = C_ T(K) Star with a temperature of 3,000K Star with a temperature of 15,000K Star with a temperature of 5,000K (for those that just want to sit there and let other students do this while they do nothing, just know that you will have to do this yourself on the test Thursday – you should practice)

Calculate the wavelength. [Wein’s Law] Max λ = C_ T(K) Star with a temperature of 3,000K = 9.67*10^-5 (967nm) Star with a temperature of 15,000K = 1.93*10^-5 (193nm) Star with a temperature of 5,000K = 580 nm (for those that just want to sit there and let other students do this while they do nothing, just know that you will have to do this yourself on the test Thursday – you should practice)

Color wavelength interval infrared~ >700nm red~ 700–635 nm orange~ 635–590 nm yellow~ 590–560 nm green~ 560–490 nm blue~ 490–450 nm violet~ 450–400 nm Ultra-violet~ <400nm

Stefan-Boltzmann Law E = σT4 E=energy σ=constant = 5.670367(13)×10−8 The total energy emitted (intensity) by an object is equal to a constant (σ) times the temperature of the object to the 4th power E = σT4 E=energy σ=constant =  5.670367(13)×10−8 T=temperature

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 11,600K approximately how many times more energy will it emit?

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 11,600K approximately how many times more energy will it emit? 11600^4 = 18106393600000000 =16 5800^4 1131649600000000

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 2,900K approximately how many times less energy will it emit?

Calculate. [Stefan-Boltzmann Law] Our sun has a surface temperature of 5,800K. If a star has a temperature of 2,900K approximately how many times less energy will it emit? 5800^4= 16 2900^4

Use Wein’s Law and Stephan-Boltzmans Law to complete your chart. Peak color Temperature (K) Wavelength Energy intensity Infrared Red Orange Yellow Green Blue Violet Ultraviolet

Things to Study: Electromagnetic Spectrum Types of electromagnetic radiation Electromagnetic Waves Properties of Waves calculating energy, wavelength and frequency Telescopes Spectroscopes and Diffraction Types of Spectrum, identifying elements with spectrum Blackbody Radiation Curves Wein’s Law and the Stefan-Boltzmann Law