A voltmeter is connected in parallel with a variable resistance R… - Vidyadip

MCQ

A voltmeter is connected in parallel with a variable resistance $R$ which is in series with an ammeter and a cell as shown in the figure. For one value of $R$, the meters read $0.3 \,A$ and $0.9 \,V$. For another value of $R$ the readings are $0.25 \,A$ and $1.0 \,V$. What is the internal resistance of the cell is ......... $\Omega$

A
$0.5$
✓
$2$
C
$1.2$
D
$1$

✓

Answer

Correct option: B.

$2$

b
(b)

$^-0.9=^-E-^+0.3 r$

$1=E-0.25 r$

$0.1=0.05 r$

$r=\frac{10}{5}=2 r$

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