Question

Two sources of equal e.m.f are connected to an external resistance R in series. The internal resistance of the two sources are R₁ and R₂ (R₂ > R₁) If the potential difference across the source having internal. resistance R₂ is zero, then ______.

Options

• R = R₁R₂/(R₁ + R₂)

• R = R₁R₂/(R₂ - R₁)

• R = R₂(R₁ + R₂)/(R₂ - R₁)

• R = R₂ - R₁

Answer 1

Two sources of equal e.m.f are connected to an external resistance R in series. The internal resistance of the two sources are R₁ and R₂ (R₂ > R₁) If the potential difference across the source having internal. resistance R₂ is zero, then R = R₂ - R₁.

Explanation:

I = `(2"E")/("R" + "R"_1 + "R"_2)`

From cell (2), E = V + IR₂ = 0 + IR₂ 

I = `(2"I")/("R" + "R"_1 + "R"_2) xx "R"_2`

⇒ R = R₂ - R₁