The resistivity of wires with Cobra SMARTsense

Principle

Based on the experimentally determined relationships R ∼ I for constant ρ and A and R ∼ 1∕A for constant ρ and l, the specific resistance was introduced as a material "constant" via R ∼ l∕A and the equation R = ρ ⋅ l∕ A was worked out.

Using this equation, the students should experimentally determine the value ρ for common conductor materials.

Tasks

1. Measure current and voltage pairs on pieces of copper, iron and constantan wire
2. Calculate the electrical resistance of the wires from the measured values
3. Determine the specific resistance using the length and cross-sectional area of the wires.

Learning objectives

Students learn experimentally how the resistance of a conductor depends on its length and cross-sectional area. They use the formula R = ρ ⋅ l∕ A to determine the resistivity ρ of different materials.

Advantages

• No additional cable connections required between the components - clearer and faster assembly
• Contact reliability thanks to components that can be interlocked like a puzzle
• Hard gold-plated, corrosion-resistant contacts
• Double learning success: electrical circuit diagram visible on the top and real components on the bottom