Question

1. (a) When counting random events, as seen in Activity B, if an average value N is found after repeating the same experiment what is the standard deviation σ?

(b) A student measures the number of heads which occur in every 300 flips of a coin to be, on average, N = 145. What is the uncertainty in the expected number of heads flipped?

(c) (i) From Activity F, what is the expression for relative uncertainty?

(ii) Suppose you are measuring radiation activity over time. If you want to decrease your relative uncertainty, should you increase or decrease the measurement time (number of total counts)?

Answer 1

1. (a) If an average value N is found after repeating the same experiment, then standard deviation will be given as :

= (1 / N) (X_i - )²

where, = mean value of observation

N = total number of obeservation

(b) What is the uncertainty in the expected number of heads flipped?

= (145) / (300)

= 0.483

(c) i. From Activity F, what is the expression for relative uncertainty?

Relative uncertainty = | uncertainty / measured quantity |

ii. Suppose we are measuring radiation activity over time. If we want to decrease our relative uncertainty, then we should increase the measurement time (number of total counts).