1. 
Using
a Ruler 

Measure the
dimensions of a sheet of A4 paper, using a ruler marked in mm. 

Results


Width (w)
= ______ mm ± ______ mm = ______ mm ± ______%
Length ()
= ______ mm ± ______ mm = ______ mm ± _______%


We are therefore
saying that the dimensions are in the following ranges 

__________ mm <
w < __________ mm
__________ mm <
< __________ mm


Now use the
minimum and maximum values of w and
to calculate the minimum and maximum values of the surface area
of a sheet of A4 paper 

____________
mm^{2} < area < ____________ mm^{2}


so we have
(indirectly) measured the area to be 

area
= ____________ mm^{2} ± __________ mm^{2} 

which could be expressed as 

area
= ____________ mm^{2} ± ________% 

Notice that the indeterminacy
(uncertainty) in the area is a greater percentage
of the result than the indeterminacies in the original
measurements of w and
. 

If you have done your calculations
correctly, you should find that 

%
indeterminacy in area = % indeterminacy in w + % indeterminacy
in



2. 
Using a Voltmeter 

Take a battery and measure its
voltage using a) the 30V calibration and b) the 7·5V
calibration. 

Results 
a) 
Scale
reading = ______ ± ____ so, voltage = ______V ± ______V 

This means that we have found 

________
V < voltage of battery < ________ V 
b) 
Scale
reading = ______ ± ____ so, voltage = ______ V ± _____ V 

This means that we now have a
smaller range of possible voltages 

________
V < voltage of battery < ________ V 

Conclusion 

__________________________________________________
__________________________________________________
__________________________________________________ 

Reading
Analogue Voltmeters 
There is a choice of six
different calibrations on the voltmeters.
The number written under each
red terminal tells you the maximum
voltage which can be measured when using that
terminal.
For example, using the 30V
red terminal, you can measure voltages between
zero and 30V. In other words, the highest number
on the scale (150) represents 30V. So, to
convert scale reading to voltages, simply divide
by 5 (150/30).
Similarly, if you are using
the 7·5V calibration, divide the scale readings
by 20 (150/7·5).
N.B. Use the mirror near the scale to help
you find the correct position from which to view
the scale. 


c) 
Try using a number of different
voltmeters to measure the voltage of the same battery. 

Voltmeter 
Scale
Reading 
Voltage
/V 

± 
± 

± 
± 

± 
± 

± 
± 

± 
± 


These results suggest that the
voltmeters used are reliable/unreliable. 


3. 
Using Vernier
Callipers 
a) 
Use a Vernier calliper to measure
the thickness of a sheet of paper. 

Thickness
of one sheet of paper = _________ mm ± _______ mm 

which
corresponds to a % uncertainty of about ________ % 
b) 
Now use the same Vernier calliper to
find the average thickness of a sheet of paper with much greater
precision. 

Total
thickness of _____ sheets of paper = _______ mm ± ____ mm 

Therefore,
we can say that the average thickness of one sheet of paper is
________ mm ± _______ mm which corresponds to a % uncertainty
of about ________ %. 
c) 
Measure the diameter of a
cylindrical object at 5 different places. 

Results 

1 
____________
mm ± __________ mm 
2 
____________
mm ± __________ mm 
3 
____________
mm ± __________ mm 
4 
____________
mm ± __________ mm 
5 
____________
mm ± __________ mm 


average
diameter ____________ mm ± __________ mm 

maximum
reading ____________ mm ± __________ mm 

minimum
reading ____________ mm ± __________ mm 

Our measurements suggest that the
manufacturers have produced cylinders with a diameter given by 

average diameter ±½(maximum
reading  minimum reading), which gives 

____________
mm ± __________ mm 

or, as a percentage 

____________
mm ± __________ mm 

Manufacturers often describe this
percentage figure as the "tolerance" of the
manufacturing process. 