3B Scientific Electroscope - Manual

3
Instruction Sheet
3B SCIENTIFIC® PHYSICS
U17250 Electroscope
6/03 ALF
®
The device is used for an introduction into the funda-
mentals of electrostatics and for displaying DC and AC
voltages as well as demonstrating the operating prin-
ciples of high voltage meters according to Braun.
1. Safety instructions
• 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 elec-
troscope in a stream of hot air (e.g. a hair dryer).
2. Description, technical data
The electroscope consists of a metal baseplate on which
the iron shielding ring for defined field distribution is
mounted. The iron ring is equipped with a 4-mm socket
for earthing purposes. The support for needle with
pivot bearing is attached electrically insulated to the
shielding ring. The pointer is suspended asymmetri-
cally and so its weight delivers the restoring moment.
Inside the electrically conductive insulator at the up-
per part of the device there is a 4-mm socket for mount-
ing the sphere and capacitor plate.
For demonstration experiments the electroscope is suit-
able for shadow projection using a point source light.
Diameter:
130 mm
2.1 Scope of supply
1 Electroscope
1 Sphere with 4-mm plug
1 Capacitor plate with 4-mm plug
1 Capacitor plate on insulating rod
3. Operation
The electroscope is charged using friction rods stati-
cally charged by various friction-inducing materials
(e.g. U11053), or using a high-voltage power supply unit
(e.g. U21060).
3.1 Charging up the electroscope by touching it
with a statically charged body
•
Attach the sphere or capacitor plate to the elec-
troscope.
• Rub the friction rod with the suitable material (PVC
or acrylic rods e.g. with plastic foil).
•
Touch the sphere or capacitor plate with the
charged rod. The pointer deflects.
• Remove the friction rod, the pointer remains de-
flected.
•
Touch the sphere with your hand. The pointer re-
turns to normal.
• When a high-voltage power supply is used then
attach the capacitor plate to the positive pole of
the power supply unit. Connect the negative pole
1 Sphere with 4-mm plug
2 Insulator
3 Shielding ring
4 Baseplate
5 Capacitor plate with 4-mm plug
6 Capacitor plate on insulating rod
7 4-mm socket
8 Support with pointer
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