Emitting to the Truth Start a new thread/topic Learning Target:
What does color tell us about the underlying structure of matter?
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Slide 3
Emitting to the Truth Read the Introduction p. 158 &
159
Slide 4
Emitting to the Truth We are going to be looking at different
sources of light. Incandescent light bulb: an electric light which
produces light with a filament wire heated to a high temperature by
an electric current passing through it, until it glows
Slide 5
Emitting to the Truth fluorescent light bulb: an low pressure
gas filled lamp that uses fluorescence to produce visible
light.
Slide 6
Emitting to the Truth sunlight: a portion of the
electromagnetic radiation given off by the Sun, particularly
infrared, visible, and ultraviolet light.
Slide 7
Emitting to the Truth We will be using a spectroscope, which is
an instrument that separates light into its constituent
wavelengths.
Slide 8
Emitting to the Truth The spectroscope will show the spectrum
of colors that make up the light that is being studied. spectrum:
the range of colors observed when white light is dispersed through
a prism Spectra is the plural of spectrum.
Slide 9
Emitting to the Truth Each element has a unique spectrum.
Spectra are like fingerprints. Spectra are characteristic
properties of substances and can be used to identify an
element.
Slide 10
Emitting to the Truth Your spectroscope has a scale on it to
show the wavelength of each color that makes up the light source.
The lines that appear are called spectral lines.
Slide 11
Emitting to the Truth Wavelength Is the distance between the
crests of waves Determines the type of electromagnetic energy
Slide 12
Emitting to the Truth Electromagnetic spectrum Visible light is
a small portion of the electromagnetic spectrum The color depends
on the wavelength
Slide 13
Emitting to the Truth Lets look at the spectra for different
elements: Emission Spectra of Elements Beloit College Emission
& Absorption Spectra Light 1 Light 2 Light 3 Light 4
Slide 14
Emitting to the Truth Set up a data table to capture the
spectrum for each light source you will be viewing. Use the
spectroscope to view the light source Use colored pencils to sketch
the spectrum in your notebook. There are 11 lights that you are
observing. Answer 5a-e p. 160 Answer R&C #1-4 Read/Notes Energy
p. 161-162 Light 1 Light 2 Light 3 Light 4
Slide 15
Incandescent Light Continuous spectrum All wavelengths are
present in the light that is emitted.
Slide 16
White Fluorescent Light Fluorescent tubes contain specific
elements producing thin line spectra with some continuous spectra
between the bright lines.
Slide 17
Hydrogen Element Tube Only 4 spectral lines are visible through
our spectroscope! Only these 4 wavelengths make up the light that
is emitted.
Slide 18
Emitting to the Truth Fluorescent tubes contain specific
elements producing thin line spectra. Incandescent Light bulbs have
a thin wire through which electricity runs and burns white-hot like
a campfire, or like the sun! Remember that each color has a
different wavelength, which means a different amount of energy
Emission spectra can tell us about the composition of objects like
stars for instance!
Slide 19
Take Home Lessons In the colored light, blue light has a
shorter wavelength = higher frequency = higher energy(compared to
red which has long wavelength) Light is Energy! We can use a prism
(or diffraction grating) to separate light into an emission
spectrum. It is very important to know that some of the light is
not visible to humans! It might be infrared, or ultraviolet
radiation!
Slide 20
Take Home Lessons Sometimes, scientists form explanations for
things they cannot observe directly. For instance, if you see a
broken window and a baseball lying inside, it might be reasonable
to infer that the ball did the damage. It is reasonable to infer
that energy is transferred from one thing to another light into
heat, or chemical energy into mechanical.
Slide 21
Energy: The Ultimate Quick Change Artist Energy is the ability
to do work Energy can be measured only by what it does Energy is
abstract - you cannot see it but you can detect it by the changes
it effects Energy can cause changes in temperature, height,
velocity, bonds in a molecule, the state of an electron around an
atom Energy is not created or destroyed - it just changes forms You
observe energy changes which lead you to make conclusions about how
energy is distributed.
Slide 22
P&P #5 5a. Were all spectra continuous? Not all spectra
were continuous. The incandescent light bulb produced a continuous
spectrum, and the fluorescent tube produced a partially continuous
spectrum.
Slide 23
P&P #5 5b. Did all spectra produce thin lines of color? The
fluorescent tubes produced thin lines of color.
Slide 24
P&P #5 5c. Did all spectra show bands of black space with
no color? No, the fluorescent tubes had bright lines, but the space
between the lines was mostly filled with color, not black
lines.
Slide 25
P&P #5 5d. Were thin lines of color always separated by the
same amount of black space? No, the thin lines of color of
different elements are separated by different amounts of black
space.
Slide 26
P&P #5 5e. Were thin lines of color always located in the
same place when comparing 2 different sources? No, thin lines for
the element and fluorescent tubes were in different locations.
Slide 27
R&C #1 What function does energy serve in the flame tests?
What function does energy serve in the different light
sources?
Slide 28
R&C #2 Think about the spectra you might see when viewing
light from flame tests. Now remember the spectra from the light
sources in this activity. Should spectra from flame tests be
similar to any of the 3 light source spectra? If so, which ones and
why?
Slide 29
R&C #3 Think about the spectrum you might see when viewing
a white hot campfire. Should the spectrum from a campfire be
similar to any of the 3 light source spectra? If so, which one or
ones and why?
Slide 30
R&C #4 Light is a form of energy. Otherwise oceans would
not warm and skin would not sunburn. Is every color of light
emitted from a light source associated with exactly the same amount
of energy? Connect your answer to evidence from flame tests and
spectra.
