Question

You are given two resistances $R_{1}$ and $R_{2} .$ By using them singly, in series and in parallel, you can obtain four resistances of $1.5\, \Omega, 2\, \Omega, 6\, \Omega$ and $8\, \Omega$. The values of $R_{1}$ and $R_{2}$ are

• A. $1\, \Omega ,\,7\, \Omega$
• B. $1.5\, \Omega,\, 6.5\, \Omega$
• C. $3\,\Omega,\,5\, \Omega$
• D. $2\,\Omega ,\,6\,\Omega$

Answer 1

Answer: (D)

$2\,\Omega ,\,6\,\Omega$

Answer 2

Let $R_{1}+ R_{2}=8\, \Omega$ ...(i)
and $\frac{R_{1} R_{2}}{R_{1}+R_{2}}=1.5\, \Omega$ ...(ii)
By using Eqs. (i) and (ii)) we obtain
$R_{1}=6\, \Omega$ and $R_{2}=2\, \Omega$