PASCO AP-8215A Gravitational Torsion Balance - Manual (Page 8)

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G r a v i t a t i o n a l T o r s i o n B a l a n c e E q u i p m e n t S e t u p
4
Leveling the Gravitational Torsion Balance
1. Release the pendulum from the locking mechanism by unscrew-
ing the locking screws on the case, lowering the locking mecha-
nisms to their lowest positions (Figure 4).
2. Adjust the feet of the base until the pendulum is centered in the
leveling sight (Figure 5). (The base of the pendulum will appear
as a dark circle surrounded by a ring of light).
3. Orient the Gravitational Torsion Balance so the mirror on the pen-
dulum bob faces a screen or wall that is at least 5 meters away.
Vertical Adjustment of the Pendulum
The base of the pendulum should be flush with the floor of the pendulum chamber. If it is not, adjust the height of
the pendulum:
1. Grasp the torsion ribbon head and loosen the
Phillips retaining screw (Figure 6a).
2. Adjust the height of the pendulum by moving
the torsion ribbon head up or down so the base
of the pendulum is flush with the floor of the
pendulum chamber (Figure 6b).
3. Tighten the retaining (Phillips head) screw.
Note: Vertical adjustment is only necessary at initial
setup and when you change the torsion ribbon or if
someone has loosened the retaining screw by mis-
take; it is not normally done during each experimental setup.
Pendulum
bob must be
centered over
the mirror
Mirror
Pendulum
Torsion
ribbon
Torsion ribbon
head
Look through the
sight to view the
reflection of the
pendulum bob in
the mirror.
Figure 5: Using the leveling sight to level
the Gravitational Torsion Balance.
Side,
Cutaway
View
Att ach to
Ea rth Gro
und.
Figure 4: Lowering the locking mechanism
to release the pendulum bob arms
Figure 6: Adjusting the height of the pendulum bob
The bottom of the pendulum
bob should be flush with the
floor of the chamber.
a
b
Grasp the torsion ribbon head
and loosen the Phillips screw.