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3. current electricity — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics3. current electricity1 Mark
MCQ
The potential difference in open circuit for a cell is $2.2\, volts$. When a $4\, ohm$ resistor is connected between its two electrodes the potential difference becomes $2\, volts$. The internal resistance of the cell will be .............. $ohm$
  • A
    $1$
  • B
    $0.2$
  • C
    $2.5$
  • ✓
    $0.4$
✓

Answer

Correct option: D.
$0.4$
d
$(4 + r)i = 2.2$ ...... $(i)$

and $4i = 2$ $ \Rightarrow $ $i = \frac{1}{2}$

Putting the value of $i$ in $(i)$, we get $r = 0.4\, ohm$.

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