Q126 / 180 · AIIMS 2019 (25 May) · Physics
A potential difference $V=100 \pm 5 \mathrm{~V}$, when applied across a resistance, gives a current $I=10 \pm 0.2 \mathrm{~A}$. What is the percentage error in $R$ ?
- A$2 \%$
- B$5 \%$
- Correct answerC$7 \%$
- D$8 \%$
Solution
Potential difference is $V=100 \pm 5 \mathrm{~V}$
Current is $I=10 \pm 0.2 \mathrm{~A}$.
Percentage error in voltage is obtained as
$\frac{\Delta V}{V}=\frac{5}{100} \times 100 \%=5 \%$
Percentage error in current is obtained as
$\frac{\Delta I}{I}=\frac{0.2}{10} \times 100 \%=2 \%$
Using, $R=\frac{V}{I}$, the percentage error in resistance is calculated as $R=5 \%+2 \%=7 \%$.
Hence, the correct answer is option: 'C'.