Measuring the test wire dimensions
Before we start adding weights to the test wire, we need to measure its dimensions.
Measure cross-sectional
area:
• We need to measure the cross-sectional area, A.
• Measure the diameter of the test wire by clicking on it at 4
different places. A micrometer will appear and its diameter is displayed on
the cross-beam.
• Record each of the measurements in your lab book or results data sheet and then calculate the mean diameter, D in meters.
• From D, you can calculate an
average cross-sectional area in metres squared:
• Record your value of A
for later.
Measure length:
• We need to know the initial length of the test wire, L.
• Measure L by dragging the mouse
down from near the top of the test wire to the top of the vernier scale (red line).
• The current length will be displayed on the cross-beam.
• Record the value of L in metres
for later.
Once you have measured A and L, go to the next page.
If you want more information on micrometers and how to read them, then check out the
following external sites:
• Ohio State University - These pages illustrate the key parts
of a micrometer, explain how to
read one and include an interactive
test. Note that imperial measurements (inches) are used.
• Networked Multimedia Information Services (NMIS) - The parts of
a micrometer and how to read one.
