Two cells of emfs 1 V and 2 V and internal resistances 2 Ω and 1 Ω… | JEE Main 2025 (3 Apr, Shift 2)

Q7JEE Main 2025 · 3 APR · SHIFT 2Easy

Cells: EMF, Internal Resistance & Combinations

Two cells of emfs 1 V and 2 V and internal resistances $2\ \Omega$ and $1\ \Omega$ , respectively, are connected in series with an external resistance of $6\ \Omega$ . The total current in the circuit is $I_1$ . Now the same two cells in parallel configuration are connected to same external resistance. In this case, the total current drawn is $I_2$ . The value of $\left(\frac{I_1}{I_2}\right)$ is $\frac{x}{3}$ . The value of $x$ is___________.

Numerical answer type. Work it out, then open the answer.

Show answer and solution

Answer: 4

Series: $I_1 = \frac{1 + 2}{6 + 2 + 1} = \frac{1}{3}\text{ A}$
Parallel: $E_{eq} = \frac{E_1/r_1 + E_2/r_2}{1/r_1 + 1/r_2} = \frac{0.5 + 2}{1.5} = \frac{5}{3}\text{ V}$ , $r_{eq} = \frac{2 \times 1}{3} = \frac{2}{3}\ \Omega$
$I_2 = \frac{5/3}{6 + 2/3} = \frac{5/3}{20/3} = \frac{1}{4}\text{ A}$
$\frac{I_1}{I_2} = \frac{4}{3} = \frac{x}{3} \Rightarrow x = 4$

Report a mistake

Cells: EMF, Internal Resistance & Combinations question from JEE Main 2025 (3 Apr, Shift 2)

More questions on Cells: EMF, Internal Resistance & Combinations