AP Physics 2 : Quantum and Nuclear Physics

Study concepts, example questions & explanations for AP Physics 2

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Example Questions

Example Question #21 : Atomic And Nuclear Physics

 A scientist takes a reading of a radioactive material, which has an activity of . 15 minutes later, it has an activity of .

Determine the activity at 25 minutes after the initial reading.

Possible Answers:

None of these

Correct answer:

Explanation:

Use the relationship:

Here, is the activity at a given time, is the initial activity, is the radioactive decay constant, and is the time passed since the initial reading.

Rearranging the equation to solve for .

Convert minutes to seconds and plug in values.

Again use the relationship:

Using the new , which is equal to 

Example Question #371 : Ap Physics 2

 A scientist takes a reading of a radioactive material, which has an activity of . 15 minutes later, it has an activity of .

Determine the half-life of this isotope.

Possible Answers:

None of these

Correct answer:

Explanation:

Use the relationship:

Here, is the activity at a given time, is the initial activity, is the radioactive decay constant, and is the time passed since the initial reading.

Rearrange the equation to solve for .

Convert minutes to seconds and pluge in values.

Use the relationship:

Plug in the calculated value for  and solve

 

Example Question #13 : Radioactive Nuclear Decay

 A scientist takes a reading of a radioactive material, which has an activity of . 15 minutes later, it has an activity of .

Determine the nuclear decay constant of this isotope.

Possible Answers:

None of these

Correct answer:

Explanation:

Use the relationship:

Here, is the activity at a given time, is the initial activity, is the radioactive decay constant, and is the time passed since the initial reading.

Rearrange the equation to solve for .

Convert minutes to seconds and plug in values.

Example Question #14 : Radioactive Nuclear Decay

A test is done on a sample of a newly discovered radioactive nuclei, which has an activity of later, it has an activity of .

Determine the half life of this nuclei.

Possible Answers:

None of these

Correct answer:

Explanation:

Using the relationship:

Here, is the activity at a given time, is the intial activity, is the radioactive decay constant, and is the time passed since the initial reading.

Rearranging the equation to solve for .

Converting minutes to seconds and plugging in values.

Using the relationship

Plugging in the calculated value for

 

Example Question #41 : Quantum And Nuclear Physics

A scientist discovers a new radioactive nuclei. She runs a test on a sample and finds it has an activity of .   later, it has an activity of .

Determine the decay constant.

Possible Answers:

None of these

Correct answer:

Explanation:

Using the relationship:

Here, is the activity at a given time, is the intial activity, is the radioactive decay constant, and is the time passed since the initial reading.

Rearranging the equation to solve for .

Converting minutes to seconds and plugging in values.

Example Question #42 : Quantum And Nuclear Physics

A scientist discovers a new radioactive nuclei. She runs a test on a sample and finds it has an activity of .   later, it has an activity of .

Determine the half life.

Possible Answers:

None of these

Correct answer:

Explanation:

Using the relationship:

Here,  is the activity at a given time,  is the intial activity,  is the radioactive decay constant, and  is the time passed since the initial reading.

Rearranging the equation to solve for .

Converting minutes to seconds and plugging in values.

Using the relationship

Plugging in the calculated value for

 

Example Question #23 : Atomic And Nuclear Physics

A scientist discovers a new radioactive nuclei. She runs a test on a sample and finds it has an activity of .   later, it has an activity of .

Determine the number of radioactive atoms in the initial sample.

Possible Answers:

None of these

Correct answer:

Explanation:

Using the relationship:

Here,  is the activity at a given time,  is the intial activity,  is the radioactive decay constant, and  is the time passed since the initial reading.

Rearranging the equation to solve for .

Converting minutes to seconds and plugging in values.

It is then necessary to use the relationship

Changing the units of the decay constant to be consistent with the activity given.

Using the initial activity and the calculated decay constant:

 

 

Example Question #18 : Radioactive Nuclear Decay

A scientist discovers a new radioactive nuclei. She runs a test on a sample and finds it has an activity of .   later, it has an activity of .

Determine the activity  after the original reading.

Possible Answers:

None of these

There will be no activity left

Correct answer:

Explanation:

Using the relationship:

Here,  is the activity at a given time,  is the intial activity,  is the radioactive decay constant, and  is the time passed since the initial reading.

Rearranging the equation to solve for .

Converting minutes to seconds and plugging in values.

Again using the relationship

Using the new

Example Question #19 : Radioactive Nuclear Decay

A test is done on a sample of a newly discovered radioactive nuclei, which has an activity of later, it has an activity of .

Determine the activity  after the initial reading.

Possible Answers:

None of these

Correct answer:

Explanation:

Using the relationship:

Here, is the activity at a given time, is the intial activity, is the radioactive decay constant, and is the time passed since the initial reading.

Rearranging the equation to solve for .

Converting minutes to seconds and plugging in values.

Again using the relationship

Using the new , which is equal to 

Example Question #20 : Radioactive Nuclear Decay

A scientist takes a sample of a newly discovered radioactive element, which has an activity of . 10 minutes later, it has an activity of .

Determine the number of radioactive nuclei in the original sample.

Possible Answers:

None of these

Correct answer:

Explanation:

Use the relationship:

Where is the activity at a given time, is the initial activity, is the radioactive decay constant and is the time passed since the initial reading.

Rearrange to solve for .

Convert minutes to seconds and plug in values.

It is then necessary to use the relationship:

Use the initial activity and the calculated decay constant:

 

 

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