A battery of internal resistance \(r\), when connected across \(2~\Omega\) resistor supplies a current of \(4~\text{A}\). When the battery is connected across a \(5~\Omega\) resistor, it supplies a current of \(2~\text{A}\). The value of \(r\) is: 
1. \(2~\Omega\) 2 \(1~\Omega\)
3. \(0.5~\Omega\) 4. zero
Subtopic:  EMF & Terminal Voltage |
 83%
From NCERT
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A student measures the terminal potential difference \(V\) of a cell (of emf \( E\) and internal resistance \(R\)) as a function of the current \(I\) flowing through it. The slope and intercept of the graph between \(V\) and \(I\), respectively, is equal to:
1. \(E\) and \(-r\)
2. \(-r\) and \(E\)
3. \(r\) and \(-E\)
4. \(-E\) and \(r\)
Subtopic:  EMF & Terminal Voltage |
 69%
From NCERT
AIPMT - 2009
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A battery is charged at a potential of \(15\) V for \(8\) hours when the current flowing is \(10\) A. The battery on discharge supplies a current of \(5\) A for \(15\) hours. The mean terminal voltage during discharges is \(14\) V. The "Watt hour" efficiency of the battery is:
1. \(80\%\)
2. \(90\%\)
3. \(87.5\%\)
4. \(82.5\%\)

Subtopic:  EMF & Terminal Voltage |
 68%
From NCERT
AIPMT - 2004
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A battery of emf \(E\) and internal resistance \(r\) is connected to a variable resistor \(R\) as shown below. Which one of the following is true​​​​​​?

           

1. Potential difference across the terminals of the battery is maximum when \(R=r\).
2. Power delivered to the resistor is maximum when \(R=r\).
3. Current in the circuit is maximum when \(R=r\).
4. Current in the circuit is maximum when \(R>>r\).
Subtopic:  EMF & Terminal Voltage |
 64%
From NCERT
PMT - 1995
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