JEE Mains · Physics · STD 12 - 3. current electricity
When an external resistance of \(5\ \Omega\) is connected across terminals of a cell, a current of \(0.25\text{ A}\) flows through it. When the \(5\ \Omega\) resistor is replaced by a \(2\ \Omega\) resistor, a current of \(0.5\text{ A}\) flows through it. The internal resistance of the cell is _______ \(\Omega\).
- A 3
- B 2
- C 1
- D 0
Answer & Solution
Correct Answer
(C) 1
Step-by-step Solution
Detailed explanation
Let the EMF of the cell be \(E\) and its internal resistance be \(r\). The current \(I\) in the circuit is given by \(I = \dfrac{E}{R + r}\). For the first case, \(R_1 = 5\ \Omega\) and \(I_1 = 0.25\text{ A}\): \(0.25 = \dfrac{E}{5 + r} \Rightarrow E = 0.25(5 + r)\) For the…
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