Question

Five resistors each of $3\Omega$, are connected as shown in the figure below. Calculate the resistance :

(a) Between points P and Q
(b) Between points X and Y
[4 MARKS]

Answer 1

Each subpart: 2 Marks each

(a) In the given circuit diagram, two resistances between PZ and QZ are connected in series. The equivalent resistance of this series combination
$=3+3=6\Omega$
The equivalent resistance is now connected in parallel with a $3\Omega$ resistor between P and Q. Then the equivalent resistance R between P and Q is given by $\frac{1}{R}=\frac{1}{6}+\frac{1}{3}=\Rightarrow R=2\Omega$
(b) Total resistance between X and Y is given by the sum of resistance of XP, YQ and the equivalent resistance between PQ,
$R^{\prime }=3+2+3=8\Omega$
So, the resistance between X and Y is $8\Omega$