Question

A combination consists of three resistors in series. Four similar sets are connected in parallel. if the resistance of each resistor is 2 ohm, the resistance of the combination is :

• A. $2.5\Omega$
• B. $3\Omega$
• C. $1.5\Omega$
• D. $5\Omega$

Answer 1

The correct option is C $1.5\Omega$

In this case, the 3 resistors of 2 ohms each are connected in series and hence the total resistance is given as 2+2+2 = 6 ohms.
Now, this combined 6 ohms resistance is connected in a parallel connection with four such series. Thus the total resistance of the parallel is connection is given as
The resistances R3 and R4 that are connected in parallel have a resistance given as $\frac{1}{6}+\frac{1}{6}+\frac{1}{6}+\frac{1}{6}=\frac{1}{0.67}=1.5ohms$.
Hence, the total resistance in the circuit is 1.5 ohms.