€¦  · Web viewExC-ELL vocabulary: Electromagnetic Energy. OBJECTIVES: Stars, Galaxies, and the Universe. NOTES: ELECTROMAGNETIC & VISIBLE-LIGHT SPECTRA (plural of spectrum) Types

Research Earth Science AgendaNovember 1, Tuesday: A Day

Take out your CH#28 Preview and vocabulary diagrams/pictures (HW)

WARM-UPS:1. ExC-ELL vocabulary: Electromagnetic Energy

OBJECTIVES: Stars, Galaxies, and the Universe1. NOTES:

a. ELECTROMAGNETIC & VISIBLE-LIGHT SPECTRA (plural of spectrum)b. Types of Visible Spectrac. Doppler Effect (if time allows)

2. WRITE AROUND ExC-ELL strategya. Listen to directions – they are printed on the sheet at your group table

HOMEWORK1. Be sure you have completed your CH#28 Preview2. Be sure you have completed your CH#28 vocabulary words (10 diagrams – list on pg. 638)

a. Be sure your picture conveys the meaning of the wordb. CREATIVITY IS ENCOURAGED!!!

HAVE A GREAT DAY

Electromagnetic Spectrum A. Electromagnetic Spectrum:

a. All forms of Radiant Energy b. Emissions (energy) from Stars in the form of WAVESc. Produced by Fusion (thermonuclear reaction: Hydrogen is fused to form Helium

in the core of stars)d. Each Wavelength ( = lambda) is a different type of radiant Energye. WAVES:

Radio Waves (longest )

Microwaves

Infra-Red red longest λ

orange

Visible Light yellow

green

blue

Ultra Violet violet shortest

X-RaysGamma Rays (shortest )

A. Hot bodies (stars) emit mostly shorter wave radiations (UV, X-ray, Visible light)

B. Cool bodies (planets) emit mostly long wave radiation (IR = ‘heat’ wave)

λ

3 Types of visible Spectra

Visible Light

Continuous Spectrum

Absorption Spectrum

Identifying elements in stars

Emission SpectrumSynonym:

Examples:

Synonym:

Examples:

1. Spectra used:

2. Description/Example:

Example:

Visible

Continuous Spectrum All wavelengths of visible

light “Rainbow” –

uninterrupted band of colors

Continuum spectrum

EMISSION Spectrum Synonym: Bright-Line spectrum Unevenly spaced lines of different colors & brightness Not all wavelengths represented “fingerprint” of elements: Every element has its OWN

(unique) emission spectrum Produced by heated (hot) gases

ABSORPTION Spectrum Synonym: Dark-line spectrum Continuous spectrum with dark bands – represents

MISSING wavelengths Produced when light from stars moves through a

cooler gaso The dark lines appear in the positions of the

stars’ emission spectral lines

Comparison of the ABSORPTION Spectra from stars to the EMISSION Spectra of the chemical elements indicates the

COMPOSTION of the Stars’ outer atmosphere

Diagram an example of a Continuous, Emission, and Absorption Spectrum at the top of each circle. Then complete the graphic organizer.

Explain the differences in wavelength (size of wave) for each color.

Heated Gas

Why do you need a prism (or water) to see the colors?

Which wavelengths are shortest?

Which wavelengths are longest?

Where does visible light fall (short to long)?

Which waves are “dangerous”? WHY?

What type of visible spectra is each of these?

How do you know?

Are any of these the SAME (have the same bright-line pattern)?

WHY?

Why do the emission lines from the gas match the absorption spectral lines?

What must be true about the gas that produces the dark-line spectrum?

What is true about the gas producing the bright-line spectrum?

How can we “SEE” visible light spectra?

Hand-Held Spectroscope

1. Definition

2. Parts of the Spectroscope

3. Spectrograph

LAB: “What’s in a Color?”

Students use hand-held spectroscopes (like the example on the previous page) to observe and draw (on a grid) the spectra they observe from:

Incandescent light bulbSunlightHeated Gas tubes containing Helium, Hydrogen, Nitrogen

(observation only), and Neon (observation only)

REVIEW http://spiff.rit.edu/classes/phys230/lectures/spectrographs/Fifteen.swf

The basic types of spectrum

When we pass light from a source through a spectrograph, we usually see one of three basic types of spectrum, depending on the nature of the source. German astronomer Gustav Kirchoff, working in the 1850s, figured out the reason for these different types of spectra. He explained the three basic types of spectra as coming from three different situations:

1. Solids, liquids, and dense gases emit light of all wavelengths, without any gaps. We call this a continuous spectrum.

2. HOT, thin gases emit light of only a few wavelengths. We call this an emission or bright line spectrum.

3. If there is a source of light behind it, a thin gas will absorb light of the same wavelengths it emits. We call this an absorption or dark line spectrum.

How can you tell what element/elements produced this spectrum?

From what you have learned about the 3 types of spectra and the SOURCE of visible light, label and indicate the location of the absorption & continuous spectra:

Interior of star

Atmosphere of star (2 locations)

Surface of star

Absorption spectrum produced

Continuous spectrum produced

Add to the diagram: What are the conditions needed for an emission spectrum to form?

DOPPLER EFFECT

What happens to the sound when the siren APPROACHES the listener?

What happens to the sound when the siren moves AWAY FROM (recedes from) the listener?

How does this apply to light?

What is occurring?

HOW does this apply to SOUND?

How does this apply to LIGHT?

WHAT does this mean?

Does this picture show RED shift or BLUE shift?

How do you know?

Is the object APPROACHING (coming toward) or RECEDING FROM (moving away from) the viewer?

Is the source of THIS spectrum approaching or receding from the viewer?

How do you know?

What is the name of this shift?

The LARGER the shift, the FASTER the object is moving TOWARD or AWAY FROM the viewer!