PASCO ES-9070 COULOMB BALANCE - Manual (Page 10)

Coulomb Balance 012-03760E
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side view top view
➅ Rotate the bottom torsion wire retainer (do not loosen
or tighten the thumbscrew) until the index line on the
counterweight vane aligns with the index line on the
index arm.
➆ Carefully turn the torsion balance on its side,
supporting it with the lateral support bar, as shown in
Figure 4. Place the support tube under the sphere, as
shown.
➇ Adjust the positions of the copper rings on the
counterweight vane to realign the index line on the
counterweight with the index line on the index arm.
➈ Place the torsion balance upright.
Slide Assembly Setup
(Refer to Figure 5)
➀
Connect the slide assembly to the torsion balance as
shown in Figure 5, using the coupling plate and
thumbscrews to secure it in position.
➁ Align the spheres vertically by adjusting the height of
the pendulum assembly so the spheres are aligned: Use
the supplied allen wrench to loosen the screw that
anchors the pendulum assembly to the torsion wire.
Adjust the height of the pendulum assembly as needed.
Readjust the height of the index arm and the magnetic
damping arm as needed to reestablish a horizontal
relationship.
➂ Align the spheres laterally by loosening the screw in
the bottom of the slide assembly that anchors the
vertical support rod for the sphere, using the supplied
allen wrench (the vertical support rod must be moved
to the end of the slide assembly, touching the white
plastic knob to access the screw). Move the sphere on
the vertical rod until it is laterally aligned with the
suspended sphere and tighten the anchoring screw.
➃ Position the slide arm so that the centimeter scale
reads 3.8 cm (this distance is equal to the diameter of
the spheres).
➄ Position the spheres by loosening the thumbscrew on
top of the rod that supports the sliding sphere and
sliding the horizontal support rod through the hole in
the vertical support rod until the two spheres just
touch. Tighten the thumbscrew.
You're now ready to experiment. The degree scale should
read zero, the torsion balance should be zeroed (the index
lines should be aligned), the spheres should be just
touching, and the centimeter scale on the slide assembly
should read 3.8 cm. (This means that the reading of the
centimeter scale accurately reflects the distance between
the centers of the two spheres.)
Figure 5. Slide Assembly Setup