POTENTIOMETER – COMPARISON OF EMFS OF TWO CELLS | 12th STANDARD | PHYSICS PRACTICAL | SAMACHEER |XII
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AIM:
To compare the emf’s of two primary cells using a potentiometer.
Formula
E1 / E2 = l1 / l2
(No unit)
Where E1 =emf of primary cell (Lechlanche cell)
E2 = emf of primary cell (Daniel cell)
l1 = balancing length for cell 1
l2 = balancing length for cell 2
Procedure
1. The connections are made according to the circuit diagram.
2. The jockey J is pressed in the first and the last wire and the opposite side deflections in the galvanometer shows that the connections are correct.
3. Lechlanche cell is included in the circuit using DPDT switch
4. The jockey is moved over the potentiometer wire to get zero deflection in the galvanometer.
5. The balancing length AJ is measured as l1.
6. Daniel cell is included in the circuit using the using the DPDT switch and the balancing length is measured as l2.
7. The experiment is repeated for six times by moving rheostat in one direction for changing the current in the circuit.
The ratio of the emf of the two cells is found from the formula E1 / E2 = l1 / l2
Result
The mean ratio of emf’s of two primary cells is ___________