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Resistance of metal is given by $R=\large\frac{V}{I}$. $V$ is potential difference, $I$ is current. In a circuit $V=(8 \pm 0.5)v$ and current is $I=(2 \pm 0.2)A$. what is value of resistance with percentage error?

\[(a)\;4 \Omega \pm 16.25 \% \quad (b)\;(4 \pm 0.7)\Omega \quad (c)\;4 \Omega \pm 0.7\%\quad (d)\;4 \Omega \pm 7\%\]

1 Answer

Resistance $=\large\frac{8}{2}$$=4 \Omega$
% error in R = % error in V + % error in I.
$\qquad\qquad\qquad=\large\frac{.5}{8} $$\times 100+ \large\frac{.2}{2} $$\times 100$
Hence the $\%$ of error is $16.25 \%$
Therefore, the correct answer is $(A)\;4 \Omega \pm 16.25 \% $
answered Jun 19, 2013 by meena.p
edited Mar 12, 2014 by balaji.thirumalai

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