Measuring Tools for physics and the uses

Measuring Tools
Have you ever added too much sugar when making your drink, or too much salt
when baking, or even too much water when making pancakes? The correct balance
of raw ingredients, both liquid and dry, will ensure not only the taste of the
product, but also the proper consistency and density. Therefore, you would
measure out your ingredients using the correct measuring tools.

Measuring Tools
In science we use measuring tools to not only to determine the length of an object or amount of a substance but to also
determine the accuracy or precision of them. Humans employ multiple tools to measure different things in the world.
When weighing a piece of paper, we would not attempt to do this using a bathroom scale as it is not sensitive enough to
detect its weight, so how sensitive a particular measuring tool is, must be taken into account. A 12-inch rule can measure
the length of a book but you would not use it to measure the diameter of a strand of hair or the thickness of your fingernail
therefore the suitability of the tool also plays a major role. Two such tools which are used in physics are the vernier
caliper and the micrometer.

The Vernier Caliper
A Vernier caliper is a precision instrument that allows you to take more precise
measurements than you could with regular rulers, it measures internal dimensions,
outside dimensions, and depth. The caliper has two sets of jaws, one set on the upper
and the other on the lower. It can measure to an accuracy of one thousandth of an inch
(upper jaw) and also one hundredth of a millimeter (lower jaw).

How to read the Vernier Caliper

As stated in the precious slide by Bob
there are different kinds of vernier
scales designed to do different jobs but
they all work the SAME way!!!!

Below is a diagram of a spoon in the lower jaws of the vernier caliper where the smallest
division on the sliding scale is 0.1 mm

▪ To take a reading on the caliper we first:
▪ Read the main scale and see where the sliding scale's zero cuts it, the main scale on a Vernier caliper typically tells
you the whole number plus the first decimal of the reading. In the circle highlighted we can see the sliding scale’s zero
cuts the main scale at 3.20cm but not exactly on the 2.
▪ We then find the first line on the sliding scale that lines up perfectly with any line on the main scale. (i.e. both lines
appear to connect making a perfect straight line joining them together) That mark tells you the value of the additional
digits. In this case the 4th
line on the sliding scale lines up perfectly with a line on the main scale
▪ We then add those 2 values together remembering that the sliding scale is a fraction of a millimeter therefore the reading
would me:

Determine the following Vernier caliper measurements. (The scales have been enlarged
for easier reading.) The Vernier caliper is calibrated in metric units (cm and mm)

▪Before you move on
please attempt the
question

Answer
▪ Following the steps given we first look at where the zero on the sliding scale cuts
the main scale
▪ This occurs just after 2.00cm since you can see that is does not fully reach 2.10cm
▪ We then look to see where the first line on the sliding scale lines up in a straight
line clearly and precisely with a line on the main scale
▪ This occurs as shown on the 7th
line, we now know the next decimal place in the
number
▪ Combining these together our answer will be 2.00cm + 0.07cm which equals
2.07cm your answer

Determine the following Vernier caliper measurements. (The scales have been enlarged
for easier reading.) The Vernier caliper is calibrated in metric units. (cm and mm

▪Before you move on please
attempt the question

• Following the steps given we first look at where the zero on the sliding cuts the
main scale
• This occurs just after 3.60cm
• We then look to see where the first line on the sliding scale lines up in a straight lin
clearly and precisely with a line on the main scale
• This occurs as shown on the 4th
line, we now know the next decimal place in the
number
• Combining these together our answer will be 3.60cm + 0.04cm which equals
Answer

Micrometer Screw Gauge
A micrometer, sometimes known as a micrometer screw gauge, is a measuring
instrument used for precision measurement. This is a measuring device used extensively
in the mechanical engineering field for measuring extremely small dimensions. It is used
to measure even smaller dimensions than the vernier calipers.

How to read the Micrometer
The micrometer has two scales the main scale and the rotating scale. The main scale is
divided into to mm while the rotating scale reads 1/100th
a mm or 0.01mm.

How to read the Micrometer
▪ Referring to the circle
▪ Read the sleeve and determine where the rotating thimble cuts the sleeve, in this case the thimble cuts the
sleeve just past 7.50mm
▪ To find the exact reading, determine where the horizontal line on the sleeve intercepts/cuts the rotating
thimble’s scale
▪ The sleeve cuts the thimble at 35 (since the scale on the thimble is in divisions of 1/100th
of a mm then the value
is 0.35mm)
▪ The final reading will be:

Determine the following micrometer screw gauge measurements. (The scales have been
enlarged for easier reading.)

Answer
▪ Following the steps given we read the sleeve first and determine where the
rotating thimble cuts the sleeve, in this case the thimble cuts the sleeve just past
the 7.50mm mark as indicated by the red arrow

Answer
▪ We then determine where the horizontal line on the sleeve intercepts/cuts the
rotating thimble scale
▪ We can see that the sleeve cuts the thimble at 24, (since the scale on the thimble is
in divisions of 1/100th
of a mm then the value is 0.24mm)

Answer
▪ Following the steps given we read the sleeve first and determine where the
rotating thimble cuts the sleeve, in this case the thimble cuts the sleeve just past
5.50mm (note that we cannot assume it has reached 6 as we cannot see the
line)
▪ We then determine where the horizontal line on the sleeve intercepts/cuts the
rotating thimble scale
▪ We can see that the sleeve cuts the thimble at 42, (since the scale on the thimble is
in divisions of 1/100th
of a mm then the value is 0.42mm)

Measuring Tools for physics and the uses

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