JEE Mains · Physics · STD 12 - Current electricity
- JEE Mains 2014
- Hard
- Numerical
A \(d.c.\) main supply of \(e.m.f.\, 220\, V\) is connected across a storage battery of \(e.m.f.\, 200\, V\) through a resistance of \(1\,\Omega \). The battery terminals are connected to an external resistance \('R'\) . The minimum value of \('R'\), so that a current passes through the battery to charge it is ............... \(\Omega\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(C) \(11\)
Step-by-step Solution
Detailed explanation
Given, \(emf\) of cell \(\mathrm{E}=200 \,\mathrm{V}\)
Internal resistance of cells \(=1 \,\Omega\)
D. C main supply voltage \(V=220\, \mathrm{V}\)
External resistance \(\mathrm{R}=?\)
\(r=\left(\frac{E-V}{V}\right) R\)
\(\mathrm{1}=\left(\frac{20}{220}\right) \times \mathrm{R}\)
\(\mathrm{R}=11 \,\Omega\)
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