Part I
1. A cell phone consists of a transmitter that emits radiation and receiver to receive signals in the form of radiation. When a call is made, the voice is converted to electrical signals which are then transmitted in the form of radio waves to the nearest cell tower by the transmitter. The tower then relays the signals to the receiver’s phone, which are then converted to electrical signals and back to sound again.
2. Cell phones emit signals using radio waves, which are composed of radio frequency (RF) energy and form a part of electromagnetic spectrum.
3. Radio-frequency energy is a non-ionizing form of radiation like visible light and microwave radiations. They are considered to be safe. X-rays and gamma rays are ionizing in nature and can cause harm to human body.
4. Ionizing radiation can tear atoms and molecules in tissues in human body and can alter chemical reactions, which is very harmful. Non-ionizing radiation does not cause this sort of a damage but it tends to heat up tissues in human body, similar to how microwaves heat up food. Exposure to high levels of radio waves causes damage to tissues as the human body is not capable to dissipate excessive heat. Radio waves may also have long term effects in human body.
5. Though the use of cell phones has been linked with health issues such as cancer, brain tumors, Parkison’s disease, fatigue, headaches etc, it is not known for sure whether cell phones cause health risks because there are different studies showing different results. To date no study could prove a direct connection between cell phone usage and any of these ailments.

Heads
200
96
54
28
13
7
4
2
1
Tails
104
42
26
15
6
3
2
1
Set Two:
Heads
200
94
44
18
11
6
5
2
2
1
Tails
106
50
26
7
5
1
3
1
Set Three:
Heads
200
103
57
36
18
8
4
2
1
Tails
97
46
21
18
10
4
2
1
Procedure:
1.
Count the number of pennies and place this number in the data table under "Number of
Nuclei in the Sample. This number represents the total number of radioactive nuclei
contained in our radioactive sample at the start. Place these pennies into a container.
2. Dump the pennies. The pennies that landed heads-up will represent decayed nuclei, the
pennies tails-up are your remaining sample. Remove the "decayed" pennies. Count and
the number of pennies that decayed and count the remaining pennies in the sample, and
place the data in the appropriate column in the data table.
Data Table
Data Table
Half-life
Number of Nuclei
Number of Nuclei in the
Number
in the Sample
Sample That Have
Decayed

Start
1
2
3
4
5
6
7
8
9
10
11
12
3. Repeat step 2 until all of the pennies have decayed.
4. Answer these questions.
1. Graph the "Number of Nuclei in the Sample" versus the "Half-life Number.' If the sample
has 1/8 of the radioactive nuclei left, how many half-lives would the sample have gone
through?

2. Each time you dumped the pennies, one half-life passed; it has been shown that the half-
life for this radioactive isotope is 20 years. In the year 2000, an archaeology team
unearths pottery and is using this isotope for radiometric dating to place the age of the
pottery. It is shown that 95% of the nuclei have decayed. Using your graph,
approximately how long ago was the pottery made?
3. While investigating the half-life of a radioactive isotope, the following data was gathered.
Graph the data; this graph should resemble the graph from your lab. Notice that you have
a y-value at X = 0. This is called a decay curve. Answer the following questions:
Time
Mass Remaining of the Isotope
(hr)
(g)
0.0
40.00
3.0
20.00
6.0
10.00
9.0
5.00
12.0
2.50
15.0
1.25
18.0
0.63
A. Approximately how much mass remains after 8.0 hours?
B. Approximately how much mass remains after 21.0 hours?
C. What is the half-life for this isotope?
Part III Cosmology
7.19 Cosmology
1. Assessment:
a.
Of the three experiments that are used to confirm the Big Bang theory, which is
the most interesting to you and why?
b. Use 10 or fewer sentences to explain your position.
2. Submit your work to the 7.19 Cosmology assessment.
Part IV
Purpose: In this activity, your goal is to apply your research and experimental findings to the
real-world issue of cell phone safety.

Introduction: Now that you have completed your investigation of atomic and nuclear physics, it
is time to relate your learning to the real-world issue of cell phone safety.
Based on your experimental results showing how radiation changes over distance, create an
informative report about how people can more safely use their cell phones. You can complete
this activity independently, or with a partner. Be sure to consult your teacher if you choose to
work with another student.
Procedure:
1. Gather research about how the public is currently made aware of cell phone radiation
levels and safety. Your research can be done on the Internet, in libraries, or at a cell
phone retail store by conducting a brief interview with a salesperson. (If an interview is
done, include your questions with your final report.)
2. In your research, address the following questions:
A. How is cell phone radiation measured, and which phones tend to present a
particularly high or low risk due to these radiation levels? (For example, you could
create High Risk and Low Risk lists of cell phones models for consumers).
B. Are the dangers of cell phone radiation made accessible and clear to the public?
3. Distance from the source of radiation has been proven to reduce the strength of that
radiation. Find evidence to justify this statement. You may select scientific articles or
possibly your own work in this course. If using an outside source, make sure you cite
your sources following the MLA Style guide.
A. What evidence did you collect to show that certain actions would help people
avoid strong exposure to radiation?
B. Based on the evidence you have collected, what can people do to use their cell
phones more safely?

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