Question

The resistance of a metal is given by $R=V/I$, where $V$ is potential difference and $I$ is the current. In a circuit, the potential difference across resistance is $V=(8\pm 0.5)V$ and current in resistance, $I=(4\pm 0.2)A$. What is the value of resistance with its percentage error?

• A. $(2\pm 5.6\%)\Omega$
• B. $(2\pm 0.7\%)\Omega$
• C. $(2\pm 35\%)\Omega$
• D. $(2\pm 11.25\%)\Omega$

Answer 1

Answer: (D)

$R=\frac{V}{I}=\frac{8}{4}=2\Omega$
$\frac{\Delta R}{R}\times 100=\frac{\Delta V}{V}\times 100+\frac{\Delta I}{I}\times 100$
$=\frac{0.5}{8}\times 100+\frac{0.2}{4}\times 100=11.25\%$
$\Rightarrow R=(2\pm 11.25\%)\Omega$