Bare Eureka (Constantan) Wire – 0.91 mm Diameter (20 SWG), 125 g Reel

This Bare Eureka (Constantan) Wire is supplied on a 125 g reel and manufactured to a 0.91 mm diameter, equivalent to 20 SWG (Standard Wire Gauge). Composed of a copper‑nickel alloy, Eureka/Constantan wire is known for its very low temperature coefficient of resistance, making it ideal for constructing precision resistance coils, bridge circuits, and Ohm’s law investigations in school laboratories.

Its stable resistance properties ensure consistent performance across a range of temperatures, making it especially suited to electrical experiments where accurate, predictable resistance is essential.

Key Features

• 125 g reel of bare Eureka/Constantan wire
• 0.91 mm diameter (20 SWG)
• Copper‑nickel alloy with low temperature coefficient
• Excellent for making resistance coils
• Provides stable, predictable resistance values
• Easy to shape, wind, and connect in experimental setups
• Ideal for physics and electronics applications

Ideal for School Science Lessons

Perfect for KS3–KS5 physics, this wire is widely used for:

• Constructing precision resistance coils
• Demonstrating Ohm’s law with consistent results
• Investigating resistivity and the effect of temperature on resistance
• Building stable bridge circuits, potentiometers, and sensors
• Comparing resistance behaviour across different wire materials

Reliable, stable, and ideal for controlled electrical investigations, this Constantan wire is an essential resource for any school physics laboratory.