Question

The potential difference across a resistor is measured to be $V=\left(\right.8\pm0.5\left.\right) \, V$ and the current through it is measured to be $I=\left(\right.2\pm0.2\left.\right) \, A$ , then the value of the resistance $R$ is

• A. $4\pm16.25\%$
• B. $4\pm6.25\%$
• C. $4\pm10\%$
• D. $4\pm8\%$

Answer 1

Answer: (A)

$V=\left(\right.8+0.5\left.\right)$
$I=\left(\right.2+0.2\left.\right)$
$R=\frac{8}{2}=4$
$\frac{\Delta R}{R}\%=\left(\frac{\Delta V}{V} + \frac{\Delta I}{I}\right)$
$=\left(\frac{0.5}{8} + \frac{0.2}{2}\right)\times 100=16.25\%$
$\therefore \, \, R=\left(\right.4\pm16.25\%\left.\right)$