Scientists such as Heinrich Hertz, Philipp Lenard, Max Planck, and Albert Einstein made scientific contributions that ultimately demonstrated that light

 discussion-  Discussion Topic

Scientists such as Heinrich Hertz, Philipp Lenard, Max Planck, and Albert Einstein made scientific contributions that ultimately demonstrated that light is electromagnetic radiation, and that it has a “dual nature.” Some electromagnetic phenomena are best explained with a particle model, and some with a wave model. In a sense, “wave” and “particle” are just easy mental models for light. We employ them because we are used to seeing waves and particles—such as those in water waves and baseballs—in our daily lives. Electromagnetic radiation is a basic concept in physics, but it doesn’t fit completely into one of these neat little boxes.

Research and discuss at least one modern technology that employs electromagnetic radiation and that can be explained by the wave model, the particle model, or a combination of the two. Some possible technologies include solar panels, burglar alarms, cameras, and cell phones.

Research Fusion and Fission Reactions

Read about Nuclear power and then search the internet for more information about fission and fusion reactions. Use the search terms:

• deuterium-tritium fusion reaction
• uranium-235 fission reaction
• plutonium-239 fission reaction

Part A

Why is the deuterium-tritium reaction the most promising nuclear fusion reaction for future energy production?

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Part B

Why is uranium-235 the most common isotope for nuclear fission in current use in nuclear power generation?

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Part C

Why is it advantageous to produce plutonium-239?

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Calculations

Complete the calculations for each nuclear reaction listed below.

Use these resources to better understand the activity at hand and to help in your tasks:

Conversions:

• 1MeV = 1.6 x 10-13 J
• Energy use per person per year in the United States = 3.5 x 1011 Joules
  (estimated, varies by source, August 2009)
• Approximate population of USA: 310,000,000

Question 1

Deuterium-Tritium Fusion Reaction

Given: energy released = 17.59 MeV per deuterium/tritium reaction pair (mass = 5 amu)

Part A

List the balanced nuclear reaction.

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Part B

Determine the energy released per kilogram of fuel used.

• Given MeV per reaction, calculate energy in joules per kilogram of reactants.
• Consider 1 mole of tritium plus 1 mole of deuterium to be a mole of “reactions” (total molar mass = 5 grams).

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Part C

Determine the mass of fuel required for the expected energy consumption in the United States for the next 10 years.

• Energy use per person per year in the United States = 3.5 × 1011 joules.
• Base your calculations on a current population of 310,000,000.

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Question 2

Uranium-235 Fission

Given: energy released = about 200 MeV per individual reaction (mass = 235 amu)

Part A

Find the balanced nuclear reaction.

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Part B

Determine the energy released per kilogram of fuel used.

• Given MeV per reaction, calculate energy in joules per kilogram of reactants.
• Consider 1 mole of uranium-235 to be a mole of “reactions” (molar mass = 235 grams).

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Part C

Determine the mass of fuel required for the expected energy consumption in the United States for the next 10 years:

• Provide the energy use per person per year in the United States = 3.5 × 1011 joules.
• Base your calculations on a current population of 310,000,000.

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Question 3

Plutonium-239

Given: energy released = about 200 MeV per individual reaction (mass = 239 amu)

Part A

List the balanced nuclear reaction.

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Part B

Determine the energy released per kilogram of fuel used.

• Given MeV per reaction, calculate energy in joules per kilogram of reactants.
• Consider 1 mole of plutonium-239 to be a mole of “reactions” (molar mass = 239 grams).

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Part C

Determine the mass of fuel required for the expected energy consumption in the United States for the next 10 years.

• Energy use per person per year in the United States = 3.5 × 1011 joules.
• Base your calculations on a current population of 310,000,000.

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Analysis and Conclusions

Write a summary of your findings from the calculations section above. Discuss information from your research and the pros and cons of each energy alternative.

Part A

Summarize the results of your calculations from Task 2.

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Part B

Discuss the pros and cons of fission and fusion reactions based on your research.

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Part C

Write your conclusions as to which nuclear reaction is the best alternative energy source.

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