Question

Resistors having resistances of $15\Omega$, $20\Omega$, and $10\Omega$ are connected in parallel. What is the effective resistance in the circuit.

Answer 1

$\frac{1}{R_{eff}}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}+\frac{1}{R_4}+......+\frac{1}{R_n}$

$\frac{1}{R_{eff}}=\frac{1}{15}+\frac{1}{20}+\frac{1}{10}\times \left(\frac{1}{2}\right)=\frac{13}{60}$

$R_{eff}=\frac{60}{13}==4.615\Omega$