In an experiment to find emf of a cell using potentiometer, the length of null point for a cell of emf 1.5 V is found to be 60 cm. If this cell is replaced by another cell of emf E , the length of null point increases by 40 cm. The value of E is x/10 V. The value of x is

Step-by-step solution

According to the principle of potentiometer, the emf of a cell is directly proportional to its balancing length. E l E₁ E₂ = l₁ l₂ Given E₁ = 1.5 V and l₁ = 60 cm. When the cell is replaced by another cell of emf E , the balancing length increases by 40 cm. l₂ = 60 + 40 = 100 cm. Substituting the values: 1.5 E = 60 100 E = 1.5 100 60 = 2.5 V. Given E = x 10 V. x 10 = 2.5 x = 25 Answer: 25