Practical 6 - Investiation of radioactive decay - a dice analogy

Question 1

What is often used instead of a dice for this practical and why?

Answer 1

Protactinium
Short enough half life

Question 2

Method for this practical

Answer 2

1. 25 virtual dice are selected
2. These are thrown - each throw represents a period of time
3. The total die showing e.g number 1 are removed and the remaining total noted (we see that the ones are “decaded”
4. This is repeated for ten “time periods” (throws)
5. The class data is collected

Question 3

Equation for the curve of best fit with this practical

Answer 3

N = Noe^-λt

Question 4

Coefficient of the x axis

Answer 4

λ

Question 5

What do we need the value of λ for?

Answer 5

To calculate the value of T1/2

Question 6

How do we calculate the value of T1/2?

Answer 6

Using T1/2 = ln (2) / λ

Question 7

What’s the problem with this practical as we did it digitally?

Answer 7

If we were plotting manually, we couldn’t get an equation for the exponential curve

Question 8

How do we get rid of the exponential?

Answer 8

Take logs

Question 9

Take logs of N = No2^-λt

Answer 9

ln (N) = ln (No) - λt

Question 10

Compare the logs of N = Noe^-λt with the equation for the line

Answer 10

ln (N) = y
ln (No) = c
λ = m
T = x

Question 11

Exponential graph initially used for N = Noe^-λt

Answer 11

Y axis = class total (N)
X axis = throws (years)

Question 12

Graph with logs taken

Answer 12

Y axis = ln (N)
X axis = throws (years)