What is Ohm's Law? Explain the verification of this law with the help of a circuit diagram.
Show Hint
Ohm's law holds true for conductors with constant resistance, but it may not apply to all materials (e.g., semiconductors or non-ohmic conductors) where the relationship between \(V\) and \(I\) is nonlinear.
Ohm's Law:
Ohm's Law states that the current (\(I\)) flowing through a conductor is directly proportional to the potential difference (\(V\)) across it and inversely proportional to its resistance (\(R\)). Mathematically, it is expressed as:
\[
V = I \cdot R
\]
where:
- \(V\) is the potential difference (voltage) across the conductor.
- \(I\) is the current flowing through the conductor.
- \(R\) is the resistance of the conductor.
Verification of Ohm's Law:
To verify Ohm’s law, we can set up a simple experiment using a circuit. The experiment involves measuring the current flowing through a resistor when a variable voltage is applied across it.
Circuit Diagram: Steps for Verification:
1. Set up a circuit with a variable power supply, a resistor (which has a known resistance \(R\)), and an ammeter to measure the current.
2. Connect a voltmeter in parallel across the resistor to measure the voltage (\(V\)) across the resistor.
3. Start with a low voltage and gradually increase it using the power supply.
4. For each voltage setting, record the corresponding current flowing through the circuit.
5. Plot the graph of voltage (\(V\)) on the y-axis and current (\(I\)) on the x-axis.
Graphical Verification:
From Ohm’s law, we know that \( V = I \cdot R \). Therefore, if we plot a graph of \(V\) versus \(I\), we should obtain a straight line with a slope equal to the resistance \(R\) of the resistor. The linear relationship indicates that the current is directly proportional to the voltage, which verifies Ohm’s law.
Conclusion:
If the graph is a straight line, then the resistance is constant, and Ohm's law is verified for that conductor.
