Question

The least resistance is obtained by using 2 ohm,4 ohm and 1 ohm in parallel combination is ________

Answer 1

As stated in the question

The resistance obtained by using the resistors in parallel :

$We\: know \:\\\frac{1}{R_{p}} =\frac{1}{R_{1}} +\frac{1}{R_{2}} +\frac{1}{R_{3}}$

$\frac{1}{R_{p}} =\frac{1}{2} +\frac{1}{4} +\frac{1}{1} \\\frac{1}{R_{p}} =\frac{2+1+4}{4} \\\frac{1}{R_{p}} =\frac{7}{4} \\R_{p}=\frac{4}{7} ohm$