Question

Two resistors of resistances $R_{1}=\left(300 \pm3\right)\,\Omega$ and $R_{2}=\left(500 \pm4\right)\,\Omega$ are connected in series. The equivalent resistance of the series combination is

• A. $\left(800 \pm 1\right)\,\Omega$
• B. $\left(800 \pm 7\right)\,\Omega$
• C. $\left(200 \pm 7\right)\,\Omega$
• D. $\left(200 \pm 1\right)\,\Omega$

Answer 1

Answer: (B)

$\left(800 \pm 7\right)\,\Omega$

Answer 2

The equivalent resistance of series combination is $R_{s}=R_{1}+R_{2}=300\,\Omega+500\,\Omega=800\,\Omega$ The error in equivalent resistance is given by $\Delta R=\left(\Delta R_{1}+\Delta R_{2}\right)=\left(3+4\right)\,\Omega=7\,\Omega$ Hence, the equivalent resistance along with error is $\left(800\pm 7\right)\,\Omega$.