Which of the following circuits is correct for verification of Ohm's law?
Show Hint
Remember the mnemonic: \textbf{A}mmeter in \textbf{S}eries (A-S) and \textbf{V}oltmeter in \textbf{P}arallel (V-P). Always ensure that the '+' terminal of every meter is electrically closer to the '+' terminal of the battery.
Step 1: Understanding the Question:
Ohm's law states that the current passing through a conductor is directly proportional to the potential difference across it, provided physical conditions remain constant (\( V = IR \)). To verify this experimentally, we need to measure both current and voltage across a known resistor. Step 3: Detailed Explanation:
To correctly measure electrical parameters in a circuit:
1. Ammeter (A): It measures the current (\( I \)) and must be connected in series with the circuit components to ensure the same current flows through it.
2. Voltmeter (V): It measures the potential difference (\( V \)) and must be connected in parallel across the resistor.
3. Polarity: The positive terminal (\( + \)) of both the ammeter and voltmeter must be connected towards the positive terminal of the power source (battery/cell).
Analyzing the provided circuit options:
- In Figure (1), the ammeter is in series and the voltmeter is in parallel. Tracing from the battery's positive terminal (the long line on the right), the current flows through the rheostat and enters the right side of the resistor. The positive terminal of the voltmeter is correctly on the right. Current leaves the left side of the resistor and enters the ammeter's positive terminal at the bottom. This configuration is correct.
- In Figure (2), the voltmeter's polarity is reversed (\( + \) is incorrectly on the left).
- In Figures (3) and (4), the ammeter is incorrectly placed in parallel across the resistor and the voltmeter is incorrectly placed in series. Step 4: Final Answer:
The correct circuit for verification of Ohm's law is shown in Figure (1).
