w the circuit diagram showing the scheme of connections as in Fig. 12.01.

clean the ends of the connecting wires with sand paper and make tight connections

according to the circuit diagram.

3. Tight the plugs of the resistance box.

1. Check the e m.f of the battery and cell and see that emf of the battery is more than

that of the given cell, otherwise null or balance point will not be obtained E>E).

5. Take maximum current from the battery, making rheostat resistance small

6. To test the correctness of the connections
(Insert the plug in the key Ki and

note the ammeter reading. Take out 2000 resistance plug from the resistance
ohm
box. Place the jockey first at the end P of the wire and then at the end Q. If the

galvanometer shows deflection in opposite directions in the two cases, the connec-

tions are correct).
that a null point is
i. Without the plug in the key adjust the rheostat so inserting
obtained the fourth wire of potentiometer.
and by slightly adjust-
on in resistance box null
nsert the 2000 ohm plug back in its position null point, obtain the jockey near the previously obtained position of