Physics Paper 2 HL Nov 2000
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(Question A1 continued)
The physicist now wishes to calculate the half-life.
(f) Define the half-life of a radioactive substance.
RRaaddiiooaaccttiivvee sosuorcuerce
GGeeigigeerr--MMuuller ttuubbee
Voltage supply and counter
(a) Define the activity of a radioactive sample.
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INTERNATIONAL BACCALAUREATE BACCALAURÉAT INTERNATIONAL BACHILLERATO INTERNACIONAL
PHYSICS HIGHER LEVEL PAPER 2
Friday 10 November 2000 (afternoon)
2 hours 15 minutes
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ln (R / s−1) 1
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5 t / hr
(c) Does the plot show that the experimental data are consistent with an exponential law?
Explain.
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Name Number
INSTRUCTIONS TO CANDIDATES
! Write your candidate name and number in the boxes above. ! Do not open this examination paper until instructed to do so. ! Section A: Answer all of Section A in the spaces provided. ! Section B: Answer two questions from Section B in the spaces provided. ! At the end of the examination, indicate the numbers of the Section B questions answered in the
(e) From the graph, determine a value for the decay constant λ.
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Physical System
Free-body Diagrams
M
M
m
m
Figure 1
Figure 2
We wish to analyse the forces in this system and derive an expression for the acceleration a of the blocks and the tension T in the cord, in terms of the variables M, m and the gravitational field strength g.
boxes below.
QUESTIONS ANSWERED SECTION A
SECTION B QUESTION QUESTION
EXAMINER
TEAM LEADER
IBCA
ALL
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(h) Hence calculate the half-life of this radioactive isotope.
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Figure 1 below shows two blocks of masses M and m, connected by a long cord over a pulley. Mass M is greater than mass m, i.e. M > m . Assume the cord and the pulley have negligible mass and that friction is negligible.
Theory predicts that the activity A of the isotope in the sample should decrease exponentially with time t according to the equation A = A0e−λt , where A0 is the activity at t = 0 and λ is the decay
(a) In Figure 2 above, draw free-body force diagrams for each block, showing and labelling all
the forces acting on each. The lengths of force vectors should reflect their comparative
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The Geiger-counter detects a proportion of the particles emitted by the source. The physicist records the count-rate R of particles detected as a function of time t and plots the data as a graph of ln R versus t, as shown below.
(d) The Geiger-counter does not measure the total activity A of the sample, but rather the
count-rate R of those particles that enter the Geiger tube. Explain why this will not matter in
A medical physicist wishes to investigate the decay of a radioactive isotope and determine its decay constant and half-life. A Geiger-Muller counter is used to detect radiation from a sample of the isotope, as shown.
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