Physics 5054/42 — October/November 2013

Cambridge O-Level · Alternative to Practical · worked solutions for every part, with the mark scheme

questions

marks

minutes

Topics Experimental Contexts · Use of Techniques, Apparatus and Materials · Observations and Measurements · Planning Experiments and Investigations · Analysis, Conclusions and Evaluation

Q1Observations and MeasurementsExperimental ContextsUse of Techniques, Apparatus and MaterialsAnalysis, Conclusions and EvaluationPlanning Experiments and InvestigationsFree sample

A student investigates how a magnetic force varies with distance.

A bar magnet is attracted to the iron base of a clamp stand, as shown in Fig. 1.1.
A newton meter is attached to the magnet.

Fig. 1.1

The student pulls the newton meter vertically upwards and measures the force $F$ required to pull the magnet off the iron base.

(a)

(i)

Explain why it is difficult to measure $F$ accurately.

(ii)

Describe a method the student can use to measure $F$ more accurately.

(b)

Fig. 1.2 shows the maximum reading on the newton meter as the magnet is pulled off the base.

Fig. 1.2

Record the force $F$ shown on the newton meter.

$F$ = ______

(c)

The student places one sheet of paper between the magnet and the iron base and measures the force $F$ to pull the magnet off the base.
He repeats the experiment, each time increasing the number $n$ of sheets of paper.
The results obtained are recorded in Fig. 1.3.

Fig. 1.3

$n$	$F / \text{N}$
0
1	3.5
2	2.5
3	1.5
4	1.0
5	0.5

On Fig. 1.3, add your value for $F$ from (b).

(i)

On Fig. 1.4, plot a graph of $F / \text{N}$ on the $y$ -axis against $n$ on the $x$ -axis.
Start your axes from the origin. Draw a smooth curve of best fit.

Fig. 1.4

(ii)

Describe how $F$ varies with $n$ .

(d)

The newton meter shown in Fig. 1.2 is not suitable for measuring $F$ when there are more than 5 sheets of paper. Suggest why.

(e)

(i)

The student repeats the experiment using paper of a different thickness. His new value of $F$ when $n = 1$ is 3.0 N. State which paper is thicker. Give a reason for your answer.

(ii)

Explain how using very thin paper improves the experiment.

(f)

Very thin sheets may be made from aluminium foil.

State and explain whether aluminium foil is a suitable material for this experiment.

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3 more questions

Q2Experimental Contexts · Use of Techniques, Apparatus and Materials · Planning Experiments and Investigations5M
Q3Observations and Measurements · Experimental Contexts · Use of Techniques, Apparatus and Materials8M
Q4Use of Techniques, Apparatus and Materials · Experimental Contexts · Observations and Measurements5M

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