Question

Three cells of emf, E, 2E and 5E having internal resistances r, 2r and 3r, variable resistance R is shown in the figure. Find the expression for the current.

Answer 1

Answer: The current is  $I = \dfrac{8E}{6r+R}$

Explanation:

Given that,

Emf of first cell = E

Emf of second cell = 2E

Emf of third cell = 5E

Internal resistance of first cell = r

Internal resistance of second cell = 2r

Internal resistance of third cell = 3r

Variable resistance = R

Now, the current

$Current = \dfrac{total\ emf}{Internal resistances + variable resistance}$

$I = \dfrac{E+2E+5E}{r+2r+3r+R}$

$I = \dfrac{8E}{6r+R}$

Hence, this is the required solution.