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Date May 2018 Marks available 1 Reference code 18M.3.SL.TZ1.1
Level Standard level Paper Paper 3 Time zone 1
Command term State Question number 1 Adapted from N/A

Question

A magnetized needle is oscillating on a string about a vertical axis in a horizontal magneticfield B. The time for 10 oscillations is recorded for different values of B.

M18/4/PHYSI/SP3/ENG/TZ1/01_01

The graph shows the variation with B of the time for 10 oscillations together with the uncertainties in the time measurements. The uncertainty in B is negligible.

Draw on the graph the line of best fit for the data.

[1]
a.

Write down the time taken for one oscillation when B = 0.005 T with its absolute uncertainty.

[1]
b.i.

A student forms a hypothesis that the period of one oscillation P is given by:

P = K B

where K is a constant.

Determine the value of K using the point for which B = 0.005 T.

State the uncertainty in K to an appropriate number of significant figures. 

[3]
b.ii.

State the unit of K.

[1]
b.iii.

The student plots a graph to show how P2 varies with 1 B  for the data.

Sketch the shape of the expected line of best fit on the axes below assuming that the relationship P = K B  is verified. You do not have to put numbers on the axes.

[2]
c.

State how the value of K can be obtained from the graph.

[1]
d.

Markscheme

smooth line, not kinked, passing through all the error bars.

[1 mark]

a.

0.84 ± 0.03 «s»

 

Accept any value from the range: 0.81 to 0.87.

Accept uncertainty 0.03 OR 0.025.

[1 mark]

b.i.

K = 0.005 × 0.84 = 0.059

« Δ K K = Δ P P »

Δ K = 0.03 0.84 × 0.0594 = 0.002

«K =(0.059 ± 0.002)» 

uncertainty given to 1sf

 

Allow ECF [3 max] if 10T is used.

Award [3] for BCA.

[3 marks]

b.ii.

s T 1 2

 

Accept s T  or in words.

[1 mark]

b.iii.

straight AND ascending line

through origin

[2 marks]

c.

K = slope

[1 mark]

d.

Examiners report

[N/A]
a.
[N/A]
b.i.
[N/A]
b.ii.
[N/A]
b.iii.
[N/A]
c.
[N/A]
d.

Syllabus sections

Core » Topic 1: Measurements and uncertainties » 1.2 – Uncertainties and errors
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Core » Topic 1: Measurements and uncertainties
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