The resistance of an ideal voltmeter is

Options

A. zero
B. infinity
C. finite, very small
D. finite and large

Answer

To determine the resistance of an ideal voltmeter, we can follow these steps:

### Step 1: Understand the Purpose of a Voltmeter
A voltmeter is used to measure the potential difference (voltage) across two points in an electrical circuit. It is designed to provide an accurate measurement without significantly affecting the circuit.

**Hint:** Remember that the primary function of a voltmeter is to measure voltage without altering the circuit's behavior.

### Step 2: Connection of a Voltmeter
A voltmeter is connected in parallel with the component across which the voltage is to be measured. This is crucial because it allows the voltmeter to measure the voltage drop without interrupting the current flow in the circuit.

**Hint:** Visualize the circuit and how the voltmeter is connected in parallel to understand its effect on the circuit.

### Step 3: Effect of Resistance on Current Flow
When a voltmeter is connected in parallel, it creates an alternative path for the current. If the voltmeter has a low resistance, it will draw a significant amount of current, which can affect the voltage reading across the component.

**Hint:** Consider what happens to the current distribution in the circuit when a low-resistance path is introduced.

### Step 4: Ideal Voltmeter Characteristics
To ensure that the voltmeter does not affect the circuit, its resistance should be extremely high (ideally infinite). This means that it will draw negligible current, allowing the circuit to operate normally while still providing an accurate voltage measurement.

**Hint:** Think about the concept of "ideal" in physics—it's a theoretical condition that helps simplify analysis.

### Step 5: Conclusion
Thus, the resistance of an ideal voltmeter is considered to be infinite. This ensures that it does not draw any current from the circuit, allowing for an accurate measurement of the voltage across the component.

**Hint:** Reflect on why an infinite resistance is a desirable characteristic for a measuring instrument in electrical circuits.

### Final Answer
The resistance of an ideal voltmeter is infinite.