The three 2 ohms are in series, therefore the total resistance is \(R=R_1+R_2+R_3\) \(R_ {total} =2+2+2= 6\) ohms. resketching circuit; 6 ohms is used to replace the three 2 ohms which is therefore placed by the 3 ohms resistor. The 3 ohms and 6 ohms resistors are in parallel, so the combined resistance is \(R=\frac{R_1xR_2}{R_1+R_2}\) \(R= \frac{3\times6}{3+6}\) \(R=\frac{18}{9}=2\) ohms. Resketching circuit: The 2 ohms is used to replace the 3 ohms and 6 ohms laying side-by-side. Therefore, the 3 resistors (1 ohm, 1 ohm, and 2 ohms) are in series. Thus, the total resistance is \(R= (R_1+R_2+R_3)\) \(R_{total} =1+1+2=4\) ohms. Therefore, the total resistance measured at PQ is 4 ohms.