Question

In ohm's law experiment, the potential drop across a resistance was measured as $V=5.0V$ and the current was measured as $i=2.00A$. Find the maximum permissible error in resistance?

• A. $R=(3.5\pm 2.5\%)\Omega$
• B. $R=(2.5\pm 2.5\%)\Omega$
• C. $R=(2.5\pm 3.5\%)\Omega$
• D. $R=(2.5\pm 5.5\%)\Omega$

Answer 1

The correct option is B $R=(2.5\pm 2.5\%)\Omega$

$R=\frac{V}{I}=\frac{5}{2}=2.5\frac{\Delta R}{R}=\frac{\Delta V}{V}+\frac{\Delta I}{I}=\frac{0.1}{5}+\frac{0.01}{2}$

$\frac{\Delta R}{R}=0.02+0.005=0.025=2.5$%

$\therefore$ $R\pm \Delta R=2.5\pm 2.5$%