3B SCIENTIFIC® PHYSICS
1
Helmholtz Pair of Coils D U19105
Instruction sheet
02/08 ALF
1 Coil
2 4-mm-sockets
3 Stand
rod
4 Securing
sleeves
1. Description
The Helmholtz coils are used to create magnetic
fields for deflecting electron beams and are at-
tached to the tube holder U19100. The tube holder
allows the coils to be set up in Helmholtz configura-
tion to generate a highly uniform magnetic field
perpendicular to the axis of the tube.
The two air-filled coils are made of lacquered cop-
per wire on a plastic bobbin on an insulating stand
rod with plastic sleeves for insertion into specially
drilled holes on the demonstration tube holder.
Connections are labelled from the start (A) to the
end (Z) of the coil winding.
2. Technical data
Number of winding
turns: 320
each
Coil diameter:
136 mm approx.
Rod:
145 mm x 8 mm Ø
Max. current:
continuous: 1.0
A
momentary:
1.5 A (max. 10 min)
2.0 A (max. 3 min)
Effective impedance:
6
Ω
approx.
Connectors: 4-mm
socket
Magnetic flux
B
in
Helmholtz-configuration:
B
=
k
*
I
, where
k
= appr. 4,2 mT/A
3. Operation
•
Insert the Helmholtz tubes into the holder with
the connections facing outwards.
•
Push the sleeves on the rod upwards and insert
the rod into the holes at an angle.
•
Push the sleeves into the holes to secure the
coils.
•
For series connection, connect socket Z of coil 1
to socket Z of coil 2 (refer to Fig 1.1).
•
Take into account the total current when calcu-
lating
B
.
•
For parallel connection, connect socket A of coil
1 to socket Z of coil 2 and socket Z of coil 1 to
socket A of coil 2 (refer to Fig 1.2).
