Question

Three resistances of 1, 2 and 3 are connected in parallel as shown in Figure
below. If the main current is 2.2A find

(a) the potential difference between P and Q

(b) the current in each of the resistances. [3 MARKS]

Answer 1

Each point: 1 Mark

Step 1: For parallel circuit, $\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}$

$\frac{1}{R_{eq}}=1+\frac{1}{2}+\frac{1}{3}$

$R_{eq}=\frac{6}{11}\Omega$

Step 2: Potential difference across $PQ=\frac{6}{11}\times 2.2=1.2V$

Step 3: Current through $1\Omega$ resistance $=\frac{V}{R_1}=1.2A$

Current through $2\Omega$ resistance= $\frac{V}{R_2}=0.6A$

Current through $3\Omega$ resistance $=\frac{V}{R_3}=0.4A$