Question

If three resistors of resistance $2\Omega ,4\Omega$ and $5\Omega$ are connected in parallel then the total resistance of the combination will be:

• A. $\frac{20}{19}\Omega$
• B. $\frac{19}{20}\Omega$
• C. $\frac{19}{10}\Omega$
• D. $\frac{10}{19}\Omega$

Answer 1

Answer: (A)

Here : Resistance of the Ist resistors $R_1=2\Omega$
Resistance of the IInd resistor $R_2=4\Omega$
Resistance of the IIIrd resistor $R_3=5\Omega$
The relation for the equivalent resistance
$R_{eq}$ of the circuit in parallel combination
$\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}$
$=\frac{1}{2}+\frac{1}{4}+\frac{1}{5}=\frac{19}{20}$
$R_{eq}=\frac{20}{19}\Omega$