AP Physics 2 : Quantum and Nuclear Physics

Study concepts, example questions & explanations for AP Physics 2

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Example Questions

Example Question #381 : Ap Physics 2

A scientist is working with a new radioactive nuclei. A sample has an activity of . 8 minutes later, it has an activity of .

Determine the nuclear decay constant.

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 #32 : Atomic And Nuclear Physics

A scientist is working with a new radioactive nuclei. A sample has an activity of . 8 minutes later, it has an activity of .

 Determine the activity 4 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 #33 : Atomic And Nuclear Physics

A scientist is working with a new radioactive nuclei. A sample has an activity of . 8 minutes later, it has an activity of .

Determine the number of radioactive atoms at the time of 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.

Rearrange the equation 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:

 

 

Example Question #34 : Atomic And Nuclear Physics

A scientist runs a test on a radioactive sample and finds that it has an activity of . Three days later, she runs another test and finds the activity to be .

Another sample is tested. It has an activity of . Determine the number of radioactive nuclei in it.

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 days to seconds and plug in values.

It is then necessary to use the relationship:

Use the initial activity and the calculated decay constant:

Example Question #35 : Atomic And Nuclear Physics

A scientist runs a test on a radioactive sample and finds that it has an activity of . Three days later, she runs another test and finds the activity to be .

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 days to seconds and plug in values.

It is then necessary to use the relationship:

Use the initial activity and the calculated decay constant:

Example Question #36 : Atomic And Nuclear Physics

A scientist runs a test on a radioactive sample and finds that it has an activity of . Three days later, she runs another test and finds the activity to be .

Determine the half-life.

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 days to seconds and plug in values.

Use the relationship:

Plugin the calculated value for :

Example Question #382 : Ap Physics 2

A scientist is working with a new radioactive nuclei. A sample has an activity of . 8 minutes later, it has an activity of .

Determine the half life.

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.

Use the relationship:

Plug in the calculated value for

Example Question #38 : Atomic And Nuclear Physics

A scientist runs a test on a radioactive sample and finds that it has an activity of . Three days later, she runs another test and finds the activity to be .

Determine the activity of the sample 12 hours after the original reading.

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 days to seconds and plug in values.

Again, use the relationship:

Use the new , which is equal to 

Example Question #39 : Atomic And Nuclear Physics

A particular radioactive sample initially has  atoms and a half-life of 30min. How many atoms are there after 2hr?

Possible Answers:

Correct answer:

Explanation:

After 1 half-life of a radioactive sample has passed, only half of the initial particles will remain. We can see that 2 hours contains four 30-minute half-life periods. Therefore, through using our equation for radioactive decay:

Example Question #392 : Ap Physics 2

A new element is discovered named Banfordium. A test is run on a sample and finds it has an activity of . Three years later, the same sample has an activity of .

Determine the decay constant of Banfordium.

Possible Answers:

None of these

Correct answer:

Explanation:

Calculate the decay constant:

Solve for

Plug in values:

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