The circuit consists of three 1.5 V cells connected in series, providing a total electromotive force (EMF) of:

Step 1: Analyze the circuit and given information.
The circuit consists of three 1.5 V cells connected in series, providing a total electromotive force (EMF) of:

$$EMF_{total} = 3 \times 1.5 \text{ V} = 4.5 \text{ V}$$

There is a parallel combination of two resistors:

• A resistor $R_1 = 2 \Omega$ (under V1).
• An unknown resistor $R_2$ (under V2). The combined parallel resistance is given as $R_{parallel} = 1.5 \Omega$. This parallel combination is in series with another resistor $R_3 = 1 \Omega$ (under V4).