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so that a desired resistance value can be obtained by withdrawing
plugs (as in a post-office bridge) or by setting multicontact switches).

3. Laboratory Bench of Wheatstone Bridge and the Pprocedure

of laboratory Experiments
The resistance box in the laboratory bench permits to receive
different values of the known resistance R from 0.01 Ω to 100000
0
Ω. The Rheostat (variable resistance) is used to change electric current
in Wheatstone bridge. Before the performance of laboratory task, the

position of rheostat should correspond to the minimum of current.
There’re two switches "rough" and "precision" on the laboratory
bench. In the beginning we set "rough" balance of the bridge, after

that, we increase the current by rheostat to "precision" balance.
The slidewire is formed in circle with the scale with 100
divisions. For example, we observe balance when l 68 mm, l 25
1 1
mm divisions and R  240 .  Therefore according to formula (6)
0
R  240   68  652 8 , .
X 25
1. Connect the components of the slidewire bridge according to

Fig. 3. In the beginning connect only one unknown resistor R .
X 1

Figure 3

2. Install the sliding contact in the middle of slidewire and
switch on "rough".

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