3B Scientific Kolbe's Electroscope - Manual (Page 2)

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4. Friction rods and rubbing material
Friction
rods Rubbing
material Charge
polarity
PVC Plastic foil +
Acrylic
glass
Plastic foil -
Glass tube
Newspaper,
leather
+
Plastic rod
Wool, textile
fibers
-
5. Operation
5.1 General notes
• Make sure that the insulator is always clean
and dry. If necessary use alcohol or spirits
for cleaning.
• At high humidity and after transporting the
unit from a cool room into a warmer one, dry
the electroscope in a stream of hot air (e.g.
a hair dryer).
5.2 Charging up the electroscope by
touching it with a statically charged body
• Attach the capacitor plate to the
electroscope.
• Rub the friction rod (e.g. 1002709) with the
suitable material (PVC or acrylic rods e.g.
with plastic foil).
• Touch the capacitor plate with the charged
rod. The pointer deflects.
• Remove the friction rod, the pointer remains
deflected.
• Touch the capacitor plate with your hand.
The pointer returns to normal.
5.3 Using electrostatic induction to charge
up the electroscope
• Approach but do not touch the capacitor
plate with the statically charged friction rod.
The pointer deflects.
• Remove the friction rod. The pointer returns
to normal.
• Again approach the capacitor plate with the
statically charged friction rod. Once again
the pointer deflects.
• Briefly touch the capacitor plate with your
finger to discharge it. The pointer deflection
disappears and returns to normal.
• Now remove the friction rod. The pointer
again shows deflection.
0 1
2
3
4
5
6
Fig. 1 Charging the electroscope using a statically-
charged friction rod
0 1
2
3
4
5
6
Fig. 2 Charging a Faraday cup (1000972)