SCEN103 Play-Doh Exercise

Resistivity and Play-Doh

Hypothesis
Anyone?

Procedure

• Roll as many of the following cylinder diameters as material and time permits:

  Sample	Diameter	Circumference
  	cm	cm
  1	0.8	2.5
  2	0.9	2.8
  3	1.0	3.1
  4	1.1	3.5
  5	1.3	4.1
  6	1.6	5.0
  7	2.0	6.3

  Cover the full range; that is, make cylinders numbers 7, 5, 3, and then 1. Fill in the intermediate values next. Make each cylinder about 12 in long; it will be necessary to measure the larger cylinders before fabricating the smaller ones.

• The quality of the experimental results will depend strongly on the uniformity of the cylinders.
  • Same diameter over the entire length
  • No cracks or voids, knead thoroughly before rolling
• After the cylinders are completed, bring to the front of the classroom for measurement in the circuit shown:
  
  • Record voltage across 10 cm of material.
  • Record current through cylinder.
  • The two measurements above should be made simultaneously!
• For each cylinder:
  • Calculate its resistance using Ohm's Law.
  • Calculate its cross-sectional area.
• On the markerboard, report:
  • Color of Play-Doh sample and names of participants.
  • Diameter (in cm), Area (in sq. cm), and resistance (in ohm) of each cylinder.
• Graph the results to test your hypothesis.