question_answer 10)

(a) In a metre bridge (Figures. the balance point is found to be at 39.5 cm from end A, when the resistor Y is of 12.5 . Determine the resistance of X. Why are the connections between resistors in a Wheatstone or meter bridge made of thick copper strips?                                 (b) Determine the balance point of the bridge above if X and Y are interchanged.                 (c) What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current?  

Answer:

                (a) (i) Using X = R we get                                                   (ii) Thick copper strips are used to reduce their resistance because this resistance is not accounted for in the calculations.                 (b) Interchanging R and X, we get                                                 i.e.,                        i.e.,                          i.e.,                        = 60.5 cm from end A.                 (c) In this case also the galvanometer will not show current.