Question

A resistance of 4 Ω and a wire of length 5 metres and resistance 5 Ω are joined in series and connected to a cell of emf 10 V and internal resistance 1 Ω. A parallel combination of two identical cells is balanced across 300 cm of the wire. The emf E of each cell is

• A. 1.5 V
• B. 3.0 V
• C. 0.67 V
• D. 1.33 V

Answer 1

Answer: (B)

3.0 V

Answer 2

By using $E_{eq} = \frac{e}{(R + R_{h} + r)}.\frac{R}{L} \times l$

⇒ $E = \frac{10}{(5 + 4 + 1)} \times \frac{5}{5} \times 3$ ⇒ E = 3 volt