A potentiometer experiment is conducted to determine the internal resis- tance of a cell. A standard cell of known EMF 1.2V is connected to the potentiometer. The null point is obtained at a length of 60 cm. When the cell being tested is connected instead of the standard cell, the null point is obtained at a length of 48 cm. Calculate the internal resistance of the cell being tested.
8.8Ω
5.0Ω
4.8 Ω
5.10 Ω
The internal resistance (r) of a cell can be calculated using the formula:
r = Length of Potentiometer Wire × Known EMF/ Change in Potentiometer Length
Substitute the given values:
Length of Potentiometer Wire = 60 cm
Known EMF = 1.2 V
Change in Potentiometer Length = 60 cm − 48 cm = 12 cm
Calculate the internal resistance:
Hence, the internal resistance of the tested cell is 6.0 Ω.
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