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Nuclear and Particle Physics

Exponential decay and radioactive dating

  • 2 things to know
  • Papers 1, 2 and 3

Overview

Recall questions on the exponential decay equations for activity and undecayed nuclei, modelling decay with dice and spreadsheets, and carbon dating and how the age of a sample is calculated.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Numbers

State the iterative equation used for modelling radioactive decay, and the initial values that must be set when modelling it on a spreadsheet.

Numbers

State the exponential decay equation for the number of undecayed nuclei N at time t.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    State the equation showing how activity varies with time.

    Model answer

    A = A₀e^(−λt)

  2. 2

    In a dice simulation of radioactive decay, what does each die represent?

    Model answer

    An undecayed nucleus.

  3. 3

    In the dice simulation, what action represents a nucleus decaying?

    Model answer

    Rolling a particular designated number, after which that die is removed.

  4. 4

    What graph is plotted from the dice simulation results and what does it show?

    Model answer

    Number of remaining dice against number of throws, showing exponential decay.

  5. 5

    Why is the dice rolling process repeated for multiple rounds?

    Model answer

    To demonstrate the random and exponential nature of radioactive decay over successive time intervals.

  6. 6

    How is the new value of N calculated in each row of a radioactive decay spreadsheet model?

    Model answer

    By adding ΔN to the previous value of N.

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