Examples of Physics Lab Reports on Ohm's Law

V = I × R

This principle is critical for designing circuits and understanding electrical components. Below are three practical examples of physics lab reports based on Ohm’s Law.

Example 1: Investigating the Resistance of a Wire

This experiment aims to measure how the length of a wire affects its resistance and to verify Ohm’s Law.

In this lab, a copper wire of varying lengths is connected to a circuit with a power supply and an ammeter to measure current. By altering the length of the wire, we can observe changes in resistance while keeping the voltage constant. The experimental setup also includes a voltmeter to measure the voltage across the wire.

After conducting the experiment, data collected includes the following:

• Length of wire (meters): 0.5, 1, 1.5, 2
• Voltage (volts): 5 (constant)
• Current (amperes): 10, 5, 3.3, 2.5

Calculating resistance using Ohm’s Law (R = V / I) yields:

• For 0.5 m: R = 5 / 10 = 0.5 Ω
• For 1 m: R = 5 / 5 = 1 Ω
• For 1.5 m: R = 5 / 3.3 ≈ 1.5 Ω
• For 2 m: R = 5 / 2.5 = 2 Ω

The results demonstrate that resistance increases with wire length, confirming Ohm’s Law.

Notes:

• Ensure all connections are secure to avoid measurement errors.
• Consider using different materials to investigate their resistivity.

Example 2: Exploring the Effect of Temperature on Resistance

This experiment examines how temperature affects the resistance of a metallic conductor, specifically a nichrome wire, in accordance with Ohm’s Law.

The setup includes a nichrome wire thermometer immersed in water, where the temperature can be gradually increased. A power supply connects to the wire, and both voltage and current are measured at various temperatures.

Data collected includes:

• Temperature (°C): 20, 40, 60, 80
• Voltage (volts): 5 (constant)
• Current (amperes): 0.25, 0.22, 0.18, 0.15

Calculating resistance at each temperature provides:

• At 20°C: R = 5 / 0.25 = 20 Ω
• At 40°C: R = 5 / 0.22 ≈ 22.73 Ω
• At 60°C: R = 5 / 0.18 ≈ 27.78 Ω
• At 80°C: R = 5 / 0.15 ≈ 33.33 Ω

The results indicate that as the temperature increases, the resistance of the nichrome wire also increases, confirming the relationship predicted by Ohm’s Law.

Notes:

• Use a thermometer for accurate temperature readings.
• Explore other materials to compare temperature effects on resistance.

Example 3: Testing Ohm’s Law with Different Resistors

This experiment aims to validate Ohm’s Law by measuring current and voltage across various resistors in a simple circuit.

A circuit is constructed using a variable resistor, a fixed resistor, and a power supply. The voltage across the resistors is varied, and current is measured using an ammeter. The setup allows for direct observation of Ohm’s Law in action.

Data collected includes:

• Resistor values (ohms): 10, 20, 30
• Voltage (volts) applied: 5, 10, 15
• Current (amperes) measured:
  • 10 Ω: 0.5 (5V), 1 (10V), 1.5 (15V)
  • 20 Ω: 0.25 (5V), 0.5 (10V), 0.75 (15V)
  • 30 Ω: 0.166 (5V), 0.333 (10V), 0.5 (15V)

Using Ohm’s Law, we can confirm:

• For 10 Ω: R = V / I = 5 / 0.5 = 10 Ω
• For 20 Ω: R = 10 / 0.5 = 20 Ω
• For 30 Ω: R = 15 / 0.5 = 30 Ω

The consistent results across different resistor values validate Ohm’s Law.

Notes:

• Maintain consistent connection quality to ensure accurate readings.
• Consider using digital multimeters for precise measurements.