Question

If the voltage and current are given by $V=(50\pm 4)V$ and $I=(20\pm 0.4)A,$ respectively, the percentage error in the resistance of conductor is

• A. 7%
• B. 10%
• C. 20%
• D. 5%

Answer 1

Answer: (A)

Given, $V=\left(50\pm 4\right)V$ $I=\left(20\pm 0.4\right)A$ Now, from Ohms law, $V=IR$ $\therefore$ $R=\frac{V}{I}$ Maximum percentage error in resistance i.e., $\frac{\Delta R}{R}\times 100=\left(\frac{\Delta V}{V}\times 100\right)+\left(\frac{\Delta I}{I}\times 100\right)$ $=\frac{4}{50}\times 100+\frac{0.4}{20}\times 100$ $=8+2=10$