Potentiometer Problem
Kirchhoff's circuit laws — worked problem Student observation in a potentiometer A student sets up a circuit as shown in the figure given below to measure the emf of a test cell. (i) Explain why he is unable to find a balance point and state the change he must make in order to achieve the balance. (ii) State how he would recognize the balance point. (iii) He obtained the balance point for distance 37.5 cm using standard cell of emf 1.50 V. And for the test cell, the balance distance AB was 25.0 cm. Calculate the emf of the test cell. (iv) He could have used an ordinary voltmeter to measure the emf of the test cell directly. The student, however, argues that the above instrument is more precise than an ordinary voltmeter. Justify his logic. (i)Problem in circuit The positive terminals of both the driving cell and the test cell must be connected to the same terminal A. If their polarities oppose each other at the joint (A...