Question

n identical cells, each of e.m.f $\epsilon$ and internal resistance r, are joined in series to form a closed circuit. The potential difference across any one cell is :

• A. Zero
• B. $\epsilon$
• C. $\frac{\epsilon }{n}$
• D. $\frac{n-1}{n}\epsilon$

Answer 1

Answer: (A)

Zero

Current in circuit, $i=\frac{n\epsilon }{nr}=\frac{\epsilon }{r}$

The equivalent circuit of one cell is shown in the figure.

The p.d. across the cell is $V_A-V_B=-\epsilon +ir=-\epsilon +\frac{\epsilon }{r}.r=0$