Two resistors of $R_1=2\Omega$ and $R_2=4\Omega$ are connected in parallel. What is the equivalent resistance of the combination?

Solution

1. The formula for parallel resistance is $\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}$.
2. Substituting the values, $\frac{1}{R_{eq}}=\frac{1}{2}+\frac{1}{4}$.
3. Calculating the sum, $$\begin{array}{rl}\frac{1}{R_{eq}}& =\frac{2+1}{4}\\ & =\frac{3}{4}\end{array}$$.
4. Therefore, $R_{eq}=\frac{4}{3}\approx 1.33\Omega$.
5. Hence the answer is (B).