Two identical cells, when connected either in parallel or in series gives same current in an external resistance 5 Ω. The internal resistance of each cell will be Ω.

Question

Two identical cells, when connected either in parallel or in series gives same current in an external resistance 5 Ω. The internal resistance of each cell will be Ω. (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/0e1f241c818a7a72cb75294386bd63d6-.png" /> i =(2 ε/5+2 r ) ldots(1) i=(ε/(r)2+5) ldots (2) Equating (1) and (2) (2 ε/5+2 r )=(ε/( r )2+5) ⇒ r +10=5+2 r r =5

Q. Two identical cells, when connected either in parallel or in series gives same current in an external resistance $5Ω$ . The internal resistance of each cell will be__ $Ω$ .

$i = \frac{2 ε}{5 + 2 r} \dots$ (1)
$i = \frac{ε}{\frac{r}{2} + 5} \dots$ (2)
Equating (1) and (2)
$\frac{2 ε}{5 + 2 r} = \frac{ε}{\frac{r}{2} + 5}$
$\Rightarrow r + 10 = 5 + 2 r$
$r = 5$

Q. Two identical cells, when connected either in parallel or in series gives same current in an external resistance 5Ω. The internal resistance of each cell will be__ Ω.

i=5+2r2ε​…(1) i=2r​+5ε​… (2) Equating (1) and (2) 5+2r2ε​=2r​+5ε​ ⇒r+10=5+2r r=5

Q. Two identical cells, when connected either in parallel or in series gives same current in an external resistance $5Ω$ . The internal resistance of each cell will be__ $Ω$ .

$i = \frac{2 ε}{5 + 2 r} \dots$ (1)
$i = \frac{ε}{\frac{r}{2} + 5} \dots$ (2)
Equating (1) and (2)
$\frac{2 ε}{5 + 2 r} = \frac{ε}{\frac{r}{2} + 5}$
$\Rightarrow r + 10 = 5 + 2 r$
$r = 5$