Radioactive decay and half-lifeAQA A-Level Physics: Mind map

Exam questions on Radioactive decay and half-life

1. A freshly prepared sample contains 4.0 × 10⁶ nuclei of a radioisotope. The decay constant of the isotope is 2.0 × 10⁻³ s⁻¹.
   Calculate the number of undecayed nuclei remaining after 600 s.2 marks
2. A student measures the activity A of a sample of a radioisotope at regular intervals. She plots a graph of ln(A / Bq) against time t in minutes and obtains a straight line with a gradient of −0.080 min⁻¹ and an intercept of 8.0 on the ln(A / Bq) axis.
   Determine the half-life of the isotope.2 marks
3. Carbon-14 has a half-life of 5730 years. Living wood contains carbon-14 and gives an activity of 0.230 Bq per gram of carbon, a value that stays constant while the tree is alive. A sample of carbon from an ancient wooden bowl gives an activity of 0.160 Bq per gram.
   Calculate the decay constant of carbon-14 in year⁻¹.3 marks