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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