Coulomb’s Law Complete Experiment

Product Code: EX-9930B


A conductive sphere is mounted on the end of an insulating, counterbalanced rod and suspended from a very thin torsion wire. An identical sphere is mounted on a calibrated linear track and can be positioned at various distances from the first sphere. When the conductive spheres are charged, the force between them is proportional to the twist of the torsion wire that is required to bring the balance back to its equilibrium position. Introductory physics students can determine the Inverse Square Law in a simple experiment, while advanced students can perform investigations into all the variables involved in electrostatic repulsion.

PASCO Advantage:
PASCO’s Coulomb’s Law Experiment features a calibrated track designed to minimize mirror charges, which can significantly affect experimental results. In addition, the conducting sphere connected to the torsion wire is magnetically damped. This allows force measurements to be made quickly, reducing the traditional difficulties with leakage currents.


  • Verify the Inverse Square Law: F ~ 1/R2
  • Verify the Force/Charge Relationship: F ~ q1q2
  • Determine Coulomb’s Constant: k = 9.0 x 109 Nm2/C2


What’s Included

Software Required

This product requires PASCO software for data collection and analysis. We recommend the following option(s). For more information on which is right for your classroom, see our Software Comparison: SPARKvue vs. Capstone »

Interface Required

This product requires a PASCO Interface to connect to your computer or device. We recommend the following option(s). For a breakdown of features, capabilities, and additional options, see our Interface Comparison Guide »

Support Documents

Manual Downloads

Product Manuals for the Included Products

Faraday Ice Pail Manual (ES-9042A)
(43 KB – .pdf – English)
Coulombs Law Apparatus Manual (ES-9070)
(240 KB – .pdf – English)
Basic Electrometer Manual (ES-9078A)
(379 KB – .pdf – English)
Experiment File
Coulomb’s Law Experiment File
(7.7 MB – .zip – English)

Included products