Five identical cells each of internal resistance 1$\Omega$ and emf 5V are connected in series and in parallel with an external resistance 'R'. For what value of 'R', current in series and parallel combination will remain the same?
Solution
${i_1} = {{25} \over {5 + R}}$<br><br>${i_2} = {5 \over {R + {1 \over 5}}}$<br><br>${i_1} = {i_2} \Rightarrow 5\left( {R + {1 \over 5}} \right) = 5 + R$<br><br>4R = R<br><br>R = 1$\Omega$
About this question
Subject: Physics · Chapter: Current Electricity · Topic: EMF and Internal Resistance
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