Step 1: Understanding the concept of an ideal voltmeter.
An ideal voltmeter is designed to measure the potential difference (voltage) across two points in a circuit without affecting the circuit itself. In order to do so, it must have no current passing through it. This ensures that the voltmeter does not draw any current from the circuit, which would alter the voltage reading.
Step 2: Reasoning behind infinite resistance.
For the voltmeter to draw no current, its internal resistance must be infinitely large. If the resistance is finite, some current would flow through the voltmeter, leading to incorrect voltage measurements and altering the current in the circuit. Thus, an ideal voltmeter has an infinite resistance.
Step 3: Conclusion.
The value of resistance for an ideal voltmeter is infinite, which allows it to measure voltage without influencing the circuit.