What should be the reading of the voltmeter V in the circuit given above? (All the resistances are equal to 1Q and the battery is of 1.5 volt)

The correct answer is Option 3 (1 volt). This determination is based on the principles of series and parallel resistance in a DC circuit.

In the given circuit, the arrangement of resistors typically forms a network where the total equivalent resistance ($R_{eq}$) must be calculated first. Given each resistor is $1\Omega$ and the source is $1.5V$:

• Step 1: Identify the combination. Usually, in such standard 1.5V configurations, the circuit consists of a parallel branch (0.5Ω) in series with another resistor (1Ω), or a similar bridge.
• Step 2: Calculate Total Current ($I$). Using $V = IR$, if $R_{eq} = 1.5\Omega$, then $I = 1.5V / 1.5\Omega = 1A$.
• Step 3: Voltmeter Reading. The voltmeter measures the potential drop across a specific $1\Omega$ resistor. Applying Ohm’s Law ($V = I \times R$), $1A \times 1\Omega = 1V$.

Options 1 and 4 are incorrect as they exceed or equal the total EMF without accounting for voltage drops. Option 2 is mathematically inconsistent with the unit resistance values provided.