Information in Radio Waves
Summative Assessment: Natural Sources of Radio
Performance expectation:
 Develop and use a model of two objects interacting through electric or magnetic fields to
illustrate the forces between objects and the changes in energy of the objects due to the
interaction.
 Student demonstrates understanding of the effects that different frequencies of
electromagnetic radiation have when absorbed by matter
Scoring Rubric:
4
All criteria from 1-3 plus:
3
2
All criteria from 1-2 plus:
All criteria from 1 plus:
1
Part 1 completed
accurately
Part1: Foundations
Rank the following types of Electromagnetic radiation from highest to lowest in terms of Energy,
Wavelength, and Frequency.
Radiation type
Radio
Energy
Wavelength
Frequency
Highest
UV
Visible
Infra-red
Lowest
Gamma
Question 1: What is the cause of all electromagnetic radiation:
a.
b.
c.
d.
Acceleration of a charged particle
Rotation of an atom
Nuclear reactions
Temperature
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Information in Radio Waves
Question 2: The following model illustrates hydrogen in its ground state.
Draw where the electron would be if it absorbed enough energy to raise it to
the first excited state.
Give 1 mechanism that could raise this electron to another energy level.
N=1
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N=2
N=3
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Question 3: Label each spectral distribution as being
either thermal or non-thermal
Question 4:
Describe the forces between the following charged particles
Pair A
Pair B
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Description:
Description:
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Information in Radio Waves
Part 2: Analyzing the Bohr model
In neutral Hydrogen, electrons can jump from one energy state to another. If in a vacuum, then the only
energy inputs or outputs will be from photons of light (EM radiation). Given the following relationships
determine the frequency of the emission line from the H1 transition line (between n=1 and n=2) seen in
the hydrogen energy level diagram.
Important relationships:
The change in energy, ΔE, from one state to another is:
∆𝐸 = 𝐸𝑖𝑛𝑖𝑡𝑖𝑎𝑙 − 𝐸𝐹𝑖𝑛𝑎𝑙 = 𝐸𝑝ℎ𝑜𝑡𝑜𝑛
Energy of a photon :
𝐸𝑝ℎ𝑜𝑡𝑜𝑛 = ℎ𝑣
Where:


h is the Planck’s constant, h = 6.626 x 10-34 Joule-seconds (J-s)
v is the frequency of the radiation in Hertz (Hz, s-1)
Energy Level Diagram of Neutral Hydrogen
Problem 1: Determine the frequency of the emission line
N=4
from the H1 transition line (between n=1 and n=2) seen in
the hydrogen energy level diagram to the left. Show all
calculations and place a box around your final answer for
the frequency.
-0.85 eV
N=3
N=2
-3.4 eV
N=1
-13.6 eV
Energy 
-1.5 eV
Principle
quantum
number
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Information in Radio Waves
Question 1: You determined a specific frequency of EM radiation coming from an excited hydrogen
atom. How could the process of absorption and emission of light be used to analyze the light from stars
and other luminous objects in space?
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Information in Radio Waves
Extention: Deciphering a radio spectrum
The graph on the right shows a generalized pattern for quasars observed over the frequencies labeled.
Use the general patterns to answer whether this source of radiation contains thermal or non-thermal
emissions.
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Quasars typically represent Active Galactic Nuclei. Is this one most likely radio ‘loud’ or radio ‘quiet’.
Justify your answer with the trends in the graph.
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