Question

A resistor of $10 \, k\Omega $ having tolerance $10\%$ is connected in series with another resistor of $20 \, k\Omega $ having tolerance $20\%$ . The tolerance of the combination will be approximately

• A. $10\%$
• B. $13\%$
• C. $17\%$
• D. $20\%$

Answer 1

Answer: (C)

$\Delta R_{s}=\Delta R_{1}+\Delta R_{2}=\left[\frac{10}{100} \times 10 + \frac{20}{100} \times 20\right]k\Omega =5k\Omega $
$\frac{ΔR_{s}}{R_{s}}\times 100=\frac{5}{30}\times 100=\frac{50}{3}=17\%$