Question

The emf of a cell is 1.5V on connecting a 14ohm resistance across the cell the terminal potential difference falls to 1.4 V calculate the internal resistance of the cell

Answer 1

Given: Emf of a cell is 1.5 V on connecting a 14 ohm resistance across the cell the terminal potential difference falls to 1.4 V .

To find: The internal resistance of the cell.

Solution:

• Now we have given:

               the potential:  V = 1.4 V

               the resistance: R = 14 ohm

               current: I = V/R = 1.4/14 = 0.1 A

• So according to the KVL rule:

               1.5 = (14 + r) x 0.1

               1.5 / 0.1 = 14 + r

               15 = 14 + r

               r = 1 ohm

Answer:

           So the internal resistance of the cell is 1 ohm.