Fri May 25, 2012 By: Namami Gaur

A) In the mt.bridge the balance point is found to be at 39.5 cm from the end A when the resistance Y is of 12.5ohm.Determine the resistance Of X.Why are the connections B/W resistors in the wheatstone bridge or mt. bridge made of the thick coper strips? B)Determine the balance point of the bridge if X & Y are interchanged. C)What happens if the the galvanometer & the cell are interchanged at the balance points of the bridge.Would the galvanometer should have any current?

Expert Reply
Fri May 25, 2012
l = 39.5 cm
R = X = ?  , Y = 12.5 ohms
S = 100-l/l * R
12.5 = (100 - 39.5/39.5) * X
So X = 8.16 ohms
The thick copper strips are used to minimize the resistance of the connections which are not accounted in the above formula.
B) If X and Y are interchanged then
R = Y = 12.5 ohms
S = X = 8.16 ohms
X = (100-l)/l * R
8.16 = (100-l)/l * 12.5
From this equation l = 60.5 cm
The galvanometer will not show any current
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