Question

While doing the parallel combination of resistors a/c to formula should we take the LCM method or divide the individual resistor and get the value?

Answer 1

Using the LCM method gives the more accurate value while dividing the individual value will also gives the same value but not always.

Two $2\Omega$ resistors in parallel

$\frac{1}{R}=\frac{1}{2}+\frac{1}{2}$

Method $1$

Taking LCM

$R=\frac{2\times 2}{2+2}$

$=1\Omega$

Method $2$

Individually dividing the values we get

$R=0.5+0.5$

$=1\Omega$

Three $3\Omega$ resistors in parallel

$\frac{1}{R}=\frac{1}{3}+\frac{1}{3}+\frac{1}{3}$

Method $1$

Taking LCM

$R=\frac{3}{3}$

$=1\Omega$

Method $2$

Individually dividing the values we get

$R=0.33+0.33+0.33$

$=0.99\Omega$