Practical - 3
LAWS OF COMBINATION OF RESISTORS
( WHEATSTONE’S BRIDGE & POST OFFICE BOX )
AIM :-
You are given a Wheatstone Bridge and other necessary instruments. Find the values of the unknown resistance Rx and Ry . Now connect them in series and parallel respectively and measure their resultant resistances and test the laws of series and parallel connections.
PRINCIPLE :- It works on the principle of a balanced Wheatstone bridge.
Apparatus :- Wheatstone-bridge (meter-bridge),
2 Volt Battery,Apparatus :- Wheatstone-bridge (meter-bridge),
Rheostat,
Galvanometer,
Jockey,
Key,
Resistance box(1 – 100 W),
Resistance coil.
 |
| Wheatstone Bridge Apparatus |
(1) Condition :- Connect unknown resistance Rx between M – N.
 |
| Wheatstone Bridge line Diagram (Condition-1) |
 |
| Wheatstone Bridge Wiring Diagram (Condition-1) |
(2) Condition :- Connect unknown resistance Ry between M – N.
 |
| Wheatstone Bridge line Diagram (Condition-2) |
 |
| Wheatstone Bridge Wiring Diagram (Condition-2) |
(3) Condition :- Connect unknown resistance in Series
 |
| Wheatstone Bridge line Diagram (Series connection) |
 |
| Wheatstone Bridge Wiring Diagram (Series connection) |
(4) Condition :- Connect unknown resistance in Parallel .
 |
| Wheatstone Bridge line Diagram (Parallel connection) |
 |
| Wheatstone Bridge Wiring Diagram (Parallel connection) |
OBSERVATION TABLE
 |
| Wheatstone Bridge Observation table |
CALCULATIONS :-
(1 (1) Series connection, R’s = Rx + Ry + …..W
(2) Parallel connection, R’p = Rx Ry / Rx + Ry = ….W.
RESULT:-
(1) Unknown resistance, Rx = ….W, Ry = ….W
 |
| Wheatstone Bridge Observation table |
CONCLUSION :
It is possible to verify the rules for series and parallel connections with the help of a meter bridge.
Precautions:-
(1) Make all connections tight.
(2) Clean the ends of the connecting wire with a sand paper.
(3) Plug keys of resistance box should be very tight.
(4) Adjust the value of R from the resistance box such that null-point is obtained between 40 cm. and 60 cm.
No comments:
Post a Comment