Write the two important precaution to be taken while performing the experiment of potentiometer
Answers
1. The first trials for balance should check the action of the protectiveresistance in both the galvanometer and the standard cell circuits toprevent injury from excessive currents.a. Care must be exercised to minimize the current passing through thestandard cell, since it is essentially an open-circuit device and its EMF isaltered by polarization resulting from current flow.b. The key should be depressed only momentarily to note the directionof needle movement; it should never be left closed.c. The maximum cell current should be limited to a value below 10microamperes, preferably to a fraction of a microampere.2.To avoid short-circuiting the standard cell, it is best to connect itto the potentiometer carefully after all other connections have been madeand to disconnect it first on dismantling the hookup. Careful checks shouldalso be made of the polarity when connecting the standard cell and theworking cell to the potentiometer. It may further be necessary to maintainthe standard cell at a constant temperature and to check its EMFperiodically