Callipers are used to measure the dimensions of objects with high precision and are often used in laboratories. Here you can learn how to use Vernier callipers to measure the widths of different samples.

Measurement is the starting point of meaningful scientific understanding. Callipers are common pieces of equipment used across science and engineering that allow object dimensions to be measured with a high degree of accuracy and precision. This can be vital for designing mechanical components or for experiments in which sample dimensions affect the outcomes, e.g. resistance or stress.

The following quick instructions are also in the downloadable file below:

- Drag moveable part of lower jaw to make jaw separation larger than sample width.
- Drag sample into lower jaws. Sample will snap into place.
- Drag moveable jaw blade to close jaws around sample.
- Read width from scale (see below for how to do this).
- Type width into ‘Sample Width’ text box and click ‘Check’ to see if you were right (green = correct, red = incorrect).
- Drag a sample out of the jaws (or press ‘Reset’) to return it to its original place and select a new sample.
- Click ‘New’ for a new set of samples with different widths.

To read the caliper scale (see full instructions for more details):

- Find the tick mark on the main scale (upper scale) that is just below the ‘zero’mark on the Vernier scale (lower scale). This gives a whole number of millimetres for sample width.
- Locate the tick mark on the Vernier scale that is most closely aligned with any tick mark on the main scale. This gives the number of tenths of a millimetre in the sample width.
- Add the values from the above steps to find the overall sample width.

Download the file below to view the full instructions for the Callipers experiment.

- Measure the width of ten samples. Check to see how many you measure correctly and give yourself a mark out of ten. Repeat this until you get 10/10 every time!
*Error analysis:*- Measure and record the width of ten or more samples.
- Use the width data to calculate the cross-sectional area of each sample.
- Determine the
*absolute error*and*fractional error*for each width measurement. - Determine the
*absolute error*and*fractional error*for each cross-sectional area value. *Statistical analysis:*- Measure and record the width of ten or more samples.
- Calculate the mean and standard deviation of the width measurements.
- (Advanced experiment) Calculate the
*standard error*of the width measurements and from this determine the confidence level of the mean.

Micrometers are used to measure the dimensions of objects with high precision. They are commonly used in laboratories. Here you can learn how to use micrometers to measure the widths of different samples.

Measurement is the starting point of meaningful scientific understanding. Micrometers are common pieces of equipment used across science and engineering that allow object dimensions to be measured with a high degree of accuracy and precision. This can be vital for designing mechanical components or for experiments in which sample dimensions affect the outcomes, e.g. resistance or stress.

The following quick instructions are also in the downloadable file below:

- Drag the
*ratchet screw*(right hand end) sideways to open or close the micrometer (the anvil part) in large steps (note that real

equipment doesn’t include this). - Click on the
*rotating**scale*and drag up or down to open or close the micrometer in small steps. - Open the micrometer and drag a sample into the anvil gap. The sample will snap into place.

- Close the micrometer around the sample. Make sure to follow use of the ratchet screw with the rotating scale to close the micrometer.
- Read width from scale (see below for how to do this).
- Type width into the appropriate text box and click ‘Check’ to see if you were right (green = correct, red = incorrect).
- Drag a sample out of the jaws (or press ‘Reset’) to return it to its original place and select a new sample.

You can also click ‘New’ for a fresh set of samples with different widths.

To read the micrometer scale (see full instructions for more details):

- Find the largest valued tick mark on the main scale that is revealed from behind the rotating thumbscrew. This gives a whole number of millimetres for sample width.
- Locate the tick mark on the rotating scale that is most closely aligned with the main scale axis. This gives the number of tenths of a millimetre in the sample width.
- Add the values from the above steps to find the overall sample width.

Download the file below to view the full instructions for the Micrometer experiment.

- Measure the diameter of ten ball bearing samples. Check to see how many you measure correctly and give yourself a mark out of ten. Repeat this until you get 10/10 every time!
*Error analysis:*- Measure and record the diameter of ten or more ball bearing samples.
- Use the width data to calculate the volume of each sphere.
- Determine the
*absolute error*and*fractional error*for each diameter measurement. - Determine the
*absolute error*and*fractional error*for each volume value. *Statistical analysis:*- Measure and record the diameter of ten or more ball bearing samples.
- Calculate the mean and standard deviation of the diameter measurements.
- (Advanced experiment) Calculate the
*standard error*of the diameter measurements and from this determine the confidence level of the mean.