Question
Two identical cells each of emf $1.5 \,V$ are connected in parallel across a parallel combination voltmeter connected in the circuit measures $1.2 \,V$.
The internal resistance of each cell is.................$\Omega$
✓
Answer
c
$V = E - ir / 2$
$V = E - ir / 2$
$1.2=1.5- i \left(\frac{ r }{2}\right)$
$i \frac{ r }{2}=0.3$
$i =\frac{1.5}{10+\frac{ r }{2}} \Rightarrow 10 i +\frac{ ir }{2}=1.5$
$10 i =1.5-0.3$
$i =0.12\, A$
$\Rightarrow r =\frac{0.6}{0.12}=5 \,\Omega$
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