To demonstrate the relationship between current, voltage, and resistance (as described by Ohm's Law), you can set up a simple experiment using a circuit that includes a variable resistor (or a set of resistors with different values), a variable power supply, an ammeter, and a voltmeter. Here's a step-by-step guide:
Experimental Setup:
1. Components Needed:
- A variable power supply (to change voltage).
- An ammeter (to measure current).
- A voltmeter (to measure voltage).
- A variable resistor or a set of resistors with different known resistances.
- Connecting wires.
- A breadboard or a circuit board (optional, for ease of setup).
2. Circuit Assembly:
- Connect the variable power supply, the resistor, and the ammeter in series to form a basic circuit.
- Connect the voltmeter in parallel with the resistor.
- Ensure all connections are secure and that the ammeter and voltmeter are correctly oriented in the circuit (observe polarity).
Method of Experimentation:
1. Initial Setup:
- Set the power supply to a low voltage to begin with.
- Record the voltage (V) across the resistor and the current (I) flowing through the circuit from the voltmeter and ammeter respectively.
2. Varying Resistance:
- Change the resistor to a different value (if using a set) or adjust the variable resistor.
- Record the new voltage (V) and current (I).
- Repeat this for multiple resistances.
3. Varying Voltage:
- Set the resistor to a fixed resistance.
- Vary the voltage using the power supply.
- Record the corresponding current each time.
- Repeat for multiple voltage settings.
4. Observations:
- Notice how the current changes with changes in voltage and resistance.
Data Interpretation and Analysis:
1. Ohm's Law Verification:
- Ohm's Law states that
, where V is voltage, I is current, and R is resistance. - For each set of readings, calculate
and compare it with the known resistance (if available).
2. Plotting:
- Plot a graph of current (I) against voltage (V) for a fixed resistance. This should be a straight line, indicating a direct relationship.
- Plot voltage (V) against resistance (R) for a fixed current. This graph will also illustrate the proportional relationship.
3. Conclusion:
- The experiment should demonstrate that as voltage increases, current increases for a given resistance, and as resistance increases, current decreases for a given voltage, adhering to Ohm's Law.
Safety Precautions:
- Do not exceed the voltage and current ratings of the components.
- Start with low voltage and gradually increase it.
- Ensure that all connections are secure to prevent short circuits.