3B Scientific Resistance Bridge - Manual

3B SCIENTIFIC® PHYSICS
1
Resistance Bridge 1009885
Instruction sheet
01/13 ALF
1 Plastic base
2 Connection sockets
3 Rail with scale
4 Resistance wire
5 Slide contact with pointer
1. Safety instructions
• Do not exceed a maximum permissible volt-
age of 8 V.
• Do not exceed a maximum permissible cur-
rent of 1.5 A.
2. Description
The resistance bridge is used in determining the
resistance in bridge circuits as well as in investi-
gating the voltage drop along a wire.
The device consists of a rail with scale mounted
on two bases with a resistance wire. A slide
contact, is attached on top of the resistance
wire. This defines the resistances R
1
and R
2
(see Fig. 1).
3. Technical data
Dimensions: approx. 1300x100x90 mm³
Rail: approx. 30x30 mm²
Scale: 0 – 1000 mm
Scale divisions: mm
Resistance wire: 1 m, 0.5 mm diam.
Material: NiCr
Resistance: 5.3
Ω
Connection: 4 mm safety jacks
Maximum voltage: 8 V
Maximum current: 1.5 A
4. Operating principle
In order to determine a resistance a Wheatstone
bridge circuit is set up (see Fig. 1).
To do this a resistance wire of length l = l
1
+ l
2
and with specific resistivity ρ (Ωm) is connected
into a circuit consisting of the resistor R
X
to be
measured and a known resistor R
0
. A DC volt-