Current Given by a Cell is considered one the most difficult concept.
22 Questions around this concept.
To verify Ohm’s law, a student connects the voltmeter across the battery as shown in the figure. The measured voltage is plotted as a function of the current and the following graph is obtained. If Vo is almost zero, then identify the correct statement.
Why is the terminal voltage of a cell generally less than the emf of the cell?
Current supplied by the cell

Cell supplies a constant current in the circuit.
$
i=\frac{E}{R+r}
$
$R$ - External resistance
$r$ - internal resistance
- Potential drop inside the cell=ir
- The internal resistance of the cell
$
r=\left(\frac{E}{V}-1\right) R
$
- Power dissipated in external resistance
$
P=\left(\frac{E}{R+r}\right)^2 R
$
- Maximum power is obtained when the resistance value of the load is equal in value to that of the voltage sources internal resistance.
Maximum power
$
P_{\max }=\frac{E^2}{4 r}
$
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