Two batteries, one of emf 18 V and internal resistance 2Ω, and the other of emf 12 V and internal resistance 1Ω, are connected as shown. The voltmeter V will record a reading of :

To find the reading on the voltmeter, we need to determine the total emf and resistance of the circuit. When two batteries are connected in series, their emfs add up, and their internal resistances also add up. So, the total emf (E_total) is 18V + 12V = 30V, and the total internal resistance (R_total) is 2Ω + 1Ω = 3Ω. However, the question doesn't explicitly state the connection is series or parallel, but based on standard circuit analysis, if we consider the batteries are connected in series (as the question implies a straightforward addition of voltages), the total resistance would be 3Ω. The current (I) in the circuit can be found using Ohm's law, I = E_total / R_total. But, to find the voltage drop across the voltmeter, we need to understand the circuit's configuration more clearly. Assuming the voltmeter is connected in parallel with one of the resistors or the batteries (though not explicitly stated), and given the lack of specific details about the circuit's configuration, the most straightforward interpretation involves calculating the total voltage and considering the voltmeter's placement. Without explicit details on how the voltmeter is connected (in series or parallel with which component), we must consider the basic principle that the voltmeter measures the voltage difference between its terminals. If we were to follow a typical analysis for series-connected batteries and assume the voltmeter is measuring the voltage across one of the batteries or a resistor in the circuit, we'd need more specific information about the circuit's configuration. Given the options and aiming for a simplified explanation, let's consider the voltmeter might be connected to measure the difference across one of the batteries or a resistor, but without explicit circuit details, we can't accurately calculate the voltage drop without making assumptions. The question seems to lack necessary details for a precise calculation based on standard circuit analysis principles.