Four different Wheatstone bridge configurations, labelled I, II, III, and IV, are initially in a balanced state. The resistance values of the four arms P , Q , R , and S for each configuration are given in the table below. Bridge P ( ) Q ( ) R ( ) S ( ) I 10 10 10 10 II 1000 1000 1000 1000 III 100 1 100 1 IV 1 100 1 100 If the resistance S is increased by exactly 0.1 in all four setups, which bridge will show the max

Step-by-step solution

The sensitivity of a Wheatstone bridge is defined by the deflection in the galvanometer for a small fractional change in resistance. A bridge is most sensitive when the resistances of all four arms are of the same order of magnitude (i.e., P Q R S ). This eliminates Bridges III and IV, which have highly unequal ratio arms. Furthermore, for a given small unbalance, a bridge with smaller absolute resistance values draws more current from the battery, leading to a larger Thevenin equivalent voltage and current across