A cell of e.m.f 1.5V, records a p.d of 1.3V, when connected to an external resistance R, such that current
flowing through circuit is 0.25A. Calculate the value of R and internal resistance of cell
Share
A cell of e.m.f 1.5V, records a p.d of 1.3V, when connected to an external resistance R, such that current
flowing through circuit is 0.25A. Calculate the value of R and internal resistance of cell
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Verified answer
Given :
EMF of the cell = 1.5V
p.d. across terminals = 1.3V
Current flow in the circuit = 0.25A
To Find :
Value of E and internal resistance of the cell
Solution :
■ For a cell of internal resistance r, the emf is
✵ e denotes emf of battery
✵ V denotes terminal voltage
✵ r denotes internal resistance
By substituting the given values;
➠ e = V + Ir
➠ 1.5 = 1.3 + 0.25r
➠ 0.25r = 1.5 - 1.3
➠ 0.25r = 0.2
➠ r = 0.2/0.25
➠ r = 0.8 Ω
■ As per ohm's law current flow in circuit is directly proportional to the applied potential difference.
Therefore, V = IR
⭆ 1.3 = 0.25R
⭆ R = 1.3/0.25
⭆ R = 5.2 Ω