Transcript MSL Electromagnetic Spectrum

Practice Questions
Electromagnetic Spectrum
The electromagnetic spectrum
Figure 3.5
Identify the following portions of the
Electromagnetic spectrum:
A
B
C
D
E
The electromagnetic spectrum
Figure 3.5
Which end of the spectrum
is more energetic, A or B? Why?
A
B
Light has a DUAL NATURE!
“photon”
&
wave
If the
Hydrogen
gas cloud is
moving
towards
Earth, the
absorption
line marked
will shift in
which
direction?
An absorption line of Hydrogen measured at rest
A
B
How do light and matter interact?
KNOW THESE DEFINITIONS!
•
•
•
•
Emission
Absorption
Transmission
Reflection or Scattering
What types of light spectra can we observe?
1. Continuous spectra
2. Absorption spectra
3. Emission spectra
Which is the absorption spectrum?
Which is the continuous spectrum?
Which is the emission spectrum?
Which spectrum is coming from the coolest object?
BLUE
Yellow
RED
BLACK
The object producing the yellow spectrum might be
what type of star?
BLUE
Yellow
RED
BLACK
Is the star producing the yellow or red spectrum
hotter? Why?
BLUE
Yellow
RED
BLACK
Which spectrum is coming from the hottest object?
BLUE
Yellow
RED
BLACK
Which star is more luminous?
T = 15,000 K
Radius = 1 unit
T = 15,000 K
Radius = 2 units
Which star is more luminous?
T = 3,000 K
Radius = 1 unit
T = 15,000 K
Radius = 1 unit
REMEMBER!
Luminosity of a star is intrinsic.
Depends on Temperature & Radius.
For which stars would we observe a Doppler Shift?
A
B
C
Doppler shift
Figure 3.18
Doppler Effect Summary
Motion toward or away from an observer causes a
shift in the observed wavelength of light:
• blueshift (shorter wavelength) 
motion _______ you
• redshift (longer wavelength)  motion AWAY
from you
• greater shift  greater speed
Doppler Effect Summary
Motion toward or away from an observer causes a
shift in the observed wavelength of light:
• blueshift (shorter wavelength)  motion toward
you
• redshift (longer wavelength) 
motion ______ from you
• greater shift  greater speed
How do telescopes help us learn about the
universe?
• Telescopes collect more light than our eyes
 light-collecting area
• Telescopes can see more detail than our eyes
 angular resolution
• Telescopes/instruments can detect light that is
invisible to our eyes (e.g., infrared, ultraviolet)
The energy source for the sun is
• A. combustion of hydrocarbons
• B. solar flares
• C. nuclear fission, the splitting of two
hydrogen atoms
• D. nuclear fusion, the joining of two
hydrogen atoms
• E. combustion of hydrogen
The energy source for the sun is
• A. combustion of hydrocarbons
• B. solar flares
• C. nuclear fission, the splitting of two
hydrogen atoms
• D. nuclear fusion, the joining of two
hydrogen atoms
• E. combustion of hydrogen
The hotter an object
• A. the brighter it appears at all wavelengths,
• B.
• C.
• D.
• E.
and the longer the wavelength at which it
appears brightest
the shorter the wavelength at which it
appears brightest
The brighter it appears at all wavelengths,
and the shorter the wavelength at which it
appears brightest
the longer the wavelength at which it
appears brightest
the brighter it appears at all wavelengths
The hotter an object
• A. the brighter it appears at all wavelengths,
• B.
• C.
• D.
• E.
and the longer the wavelength at which it
appears brightest
the shorter the wavelength at which it
appears brightest
The brighter it appears at all wavelengths,
and the shorter the wavelength at which it
appears brightest
the longer the wavelength at which it
appears brightest
the brighter it appears at all wavelengths
An object emits an emission line
spectrum. If the object moves towards
an observer,
• A. the observed emission lines shift to
shorter wavelengths
• B. the observed emission lines shift to longer
wavelengths
• C. the emission line spectrum shifts to a
continuous spectrum
• D. the emission line spectrum shifts to
an absorption line spectrum
An object emits an emission line
spectrum. If the object moves towards
an observer,
• A. the observed emission lines shift to
shorter wavelengths
• B. the observed emission lines shift to longer
wavelengths
• C. the emission line spectrum shifts to a
continuous spectrum
• D. the emission line spectrum shifts to
an absorption line spectrum
Which of the following is ordered by
increasing wavelength?
•
•
•
•
A.
B.
C.
D.
infrared, visible, radio, gamma-ray
visible, infrared, radio, gamma-ray
gamma-ray, visible, infrared, radio
radio, visible, infrared, gamma-ray
Which of the following is ordered by
increasing wavelength?
•
•
•
•
A.
B.
C.
D.
infrared, visible, radio, gamma-ray
visible, infrared, radio, gamma-ray
gamma-ray, visible, infrared, radio
radio, visible, infrared, gamma-ray
An atom is ionized if
•
•
•
•
A.
B.
C.
D.
it has lost a proton
it has lost an electron
it has lost a neutron
it has absorbed a photon
An atom is ionized if
•
•
•
•
A.
B.
C.
D.
it has lost a proton
it has lost an electron
it has lost a neutron
it has absorbed a photon