Question

Two cells of same emf but different internal resistances r₁ and r₂ are connected in series with a resistance R. The value of resistance R, for which the potential difference across second cell is zero, is ______.

विकल्प

• r₂ - r₁  

• r₁ - r₂  

• r₁  

• r₂

Answer 1

Two cells of same emf but different internal resistances r₁ and r₂ are connected in series with a resistance R. The value of resistance R, for which the potential difference across second cell is zero, is r₂ - r₁.

Explanation:

We have 

i = `("E"_"net")/("R"_"net")=(2"E")/("R"+x_1+x_3)`

As. P.d across second cell = 0

⇒ E - ir₂ = 0  [∵ V = E - iR] 

⇒ E - `(2"Er"_2)/("R"+"r"_1+"r"_2)` = 0

⇒ R + r₁ + r₂ - 2r₃ = 0 

⇒ R = r₂ - r₁