Question

Two sources of current of equal emf are connected in series and having different internal resistance r_1 and r_2(r_2gtr_1). Find the external resistance R at which the potential difference across the terminals of one of the sources becomes equal to zero.

Answer 1

Given  :

Emf = E

Potential difference = V

Current = I

r₂ > r₁

To find:

The external resistance R

Solution :

• The emf and current for both the sources are same.So the potential difference will be zero for internal resistance which is higher.

• E - ir₂ = 0

• E = ir₂   = 2Er₂ / (R+r₁-r₂)

• R+r₁+r₂ = 2r₂

• R = r₂-r₁
• The external resistance R=r₂-r₁