During the construction of long bridges, why are the two ends of a bridge not fixed rigidly in the concrete?

Give two important functions of salt bridge.

In a metre-bridge [Fig. (a)], the balance point is found to be at 39.5 cm from the end A, when the resistor S is of 12.5Omega Determine the resistance of R. Why are the connections between the resistors in a Wheatstone bridge or metre-bridge made of thick copper strips?

Draw Wheatstone bridge circuit and write down the balancing condition of it. In a meter bridge the balance point is found to be at 40 cm from one end when the resistor at the end is 10 Omega . Find the resistance at the other side. If the galvanometer and the cell are interchanged at the balance condiotion, would it affect the current through the galvanometer?

Why is salt-bridge used?

The probability of a bomb hitting a target is 0.2. Two direct hits are necessary to destroy a bridge. If six bombs are aimed at the bridge, find the probability that the bridge is destroyed.

A 1 m long wire is clamped at both ends. Find out the positions of two bridges that will divide the wire in three parts such that the fundamental frequencies are in the ratio 1 : 2 : 3 .

A null point is obtained when two resistors , of resistance r each, are connected in series and placed in the fourth arm of a wheatstone bridge . Now , the resistance R of the third arm is kept fixed ,and r, connected in parallel, are placed in the fourth arm. then a null point is obtained only by interchanging the resistances P and Q , and also the value of r.