MCQ
In given diagram ideal voltmeter $V$ reads $1.45\,V$ then relation between $r_1$ and $r_2$ is
- A$r_1 = 2r_2$
- ✓$r_1 = 3r_2$
- C$r_2 = 2r_1$
- D$r_2 = 3r_1$
✓
Answer
Correct option: B.
$r_1 = 3r_2$
b
By parallel combination
By parallel combination
$I=\frac{1.5-1.3}{r_{1}+r_{2}}=\frac{0.2}{r_{1}+r_{2}}$
$\mathrm{V}=1.3+\mathrm{Ir}_{1}$
$1.45=1.3+\frac{0.2 \mathrm{r}_{1}}{\mathrm{r}_{1}+\mathrm{r}_{2}}$
$\Rightarrow 0.15=\frac{0.2 \mathrm{r}_{1}}{\mathrm{r}_{1}+\mathrm{r}_{2}}$
$\Rightarrow 3\left(\mathrm{r}_{1}+\mathrm{r}_{2}\right)=4 \mathrm{r}_{1}$
$\Rightarrow 3 r_{2}=r_{1}$
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