STEM Course Materials List: Metal Focus

Background

Practical experimentation is essential in STEM education, especially physics, where abstract ideas such as force, conductivity, and thermal properties are concrete. To effectively learn about mechanics, electromagnetism, and optics, having actual materials that represent them is invaluable. One group of materials with diverse applications is metal samples such as copper, aluminium, and titanium alloys. They can be utilised to demonstrate variation in density, strength, electrical conductivity, and thermal conductivity, correlating theory with practice.

Topic Overview

Since physics dominates the STEM education in this case, students should have good information about material properties. Using metal samples, students can:

•Make comparisons of densities to predict how materials will perform under weight and volume conditions.

•Perform tests on mechanical strength and study stress-strain in metals.

•Experiment with electrical conductivity and why copper wires are used for electronics.

•Test thermal conductivity, illustrating why aluminium is used in heat sinks.

By associating these characteristics with everyday applications—such as aerospace, electronics, and construction—students can see the relevance of fundamental physics principles.

Required Materials

Optional: clamps, insulating mats, and safety gloves for metal sample handling during experiments. For more advanced materials, please check Stanford Advanced Materials (SAM).

Step-by-Step Instructions

1.Density Measurement

To determine the density of metal samples and compare with theoretical values, you will require a digital balance, caliper or ruler, graduated cylinder (to quantify water displacement), and your metal samples (aluminium, copper, and Ti-6Al-4V). Density is mass over volume.

Step 1: Mass measurement

Turn the digital balance on and zero it out.

Place each metal sample onto the balance and determine its mass ((m)) in grams (g).

Take the measurement twice for accuracy.

Step 2: Volume measurement

For samples of regular shape (cubes, cylinders):

•Record the measurements (length, width, height, or diameter) using a caliper or a ruler.

•Apply the appropriate geometric formula to find the volume (V).

For samples of irregular shape:

•Put a known amount of water in a graduated cylinder.

•Submerge the sample completely and read the volume change.

•The difference is the volume of the sample in cubic centimetres (cm³).

Step 3: Find the density

Use the formula:

ρ= m/V

where ρ is density in g/cm³, m is mass in grams, and V is volume in cm³.

Calculate for each metal sample.

Step 4: Compare with theoretical values

• Copper: ~8.96 g/cm³

• Aluminium: ~2.70 g/cm³

• Titanium Alloy (Ti-6Al-4V): ~4.43 g/cm³

Explain any discrepancies and possible sources of error (precision of the measurement, air bubbles, etc.).

2.Demonstration of Mechanical Strength

To explore mechanical strength and elasticity, employ a simple lever or spring system, masses, and a ruler or dial gauge to measure deformation readings. This experiment demonstrates how materials respond to the addition of stress.

Step 1: Set up the equipment

Construct a simple lever system or utilise a beam supported at both ends.

Place the metal sample in the region where force should be applied and fix it strongly.

Step 2: Gradual increase of force

Gradually add weight or apply pressure on the middle point of the beam.

Observe and record whenever there is apparent bending or deformation.

Step 3: Record data

Measure the force (F) and corresponding deflection (ΔL) at each step.

Repeat the test on each of the metal samples.

Step 4: Observe results

Comment on the stress-strain relationship and compare the stiffness through Young's modulus (E):

• Copper: ~110–130 GPa

• Aluminium: ~69 GPa

• Ti-6Al-4V: ~110 GPa

Explain why some materials bend more easily and some resist deformation.

Further reading: The 10 Strongest Materials Known To Man

3. Electrical Conductivity Test

To perform an electrical conductivity test and sample comparison, you will need a DC power supply, multimeter(s), alligator clip wires, and your metal samples. Conductivity is derived from measured voltage, current, and sample geometry.

Step 1: Connect the circuit

• Create a series circuit: put the power supply, metal sample, and multimeter in one loop.

• To measure current (I), the multimeter needs to be in series.

• To measure voltage (V), place the probes parallel to one another across the sample.

If there is only a single multimeter available, measure voltage and current in separate measurements.

Step 2: Measure current and voltage

• Place the multimeter on the correct mode (DC voltage or current).

• Measure the current through the circuit and the voltage drop on the sample.

Step 3: Calculate conductivity

1. Use Ohm's law to calculate resistance:

R = V/I

2. Use the formula for conductivity:

σ = L/(R*A)

where (L) = sample length, (A) = cross-sectional area, (R) = resistance.

Step 4: Compare results

Expected conductivities:

• Copper: ~5.96 × 10⁷ S/m (very high)

• Aluminium: ~3.5 × 10⁷ S/m

• Ti-6Al-4V: ~1.8 × 10⁶ S/m (much lower)

Discuss why conductivity varies—using atomic structure and electron mobility.

4. Thermal Conductivity Observation

This experiment demonstrates the speed at which heat is transmitted in different metals. You will need a heat source (e.g., hot plate), thermometer or thermal probe, and metal rods of the same size.

Step 1: Prepare samples

Place copper, aluminium, and Ti-6Al-4V samples of about the same size on a heat-resistant area.

Insert temperature sensors along their length.

Step 2: Introduce heat

Heat one end of each sample slowly while keeping the others at room temperature.

Supply equal heating time and intensity.

Step 3: Measure temperature distribution

Measure temperatures along the rods at equal time intervals (e.g., 10 seconds).

Notice how rapidly the far end of each specimen heats up.

Step 4: Compare and analyse

Explain thermal conductivity and efficiency of energy transfer:

• Copper: ~401 W/m·K

• Aluminium: ~237 W/m·K

• Ti-6Al-4V: ~6.7 W/m·K

Explain why copper heats up most rapidly and titanium alloy most slowly in terms of lattice vibration and bonding.

Frequently Asked Questions

Q: What makes metals valuable for laboratory and industrial applications?

A: Their strength, conductivity, and density make them appropriate for wiring, surgical devices, and chemical reactors.

Q: What relationship do electrical and thermal conductivities have with atomic structure?

A: Free-electron metals (such as copper and aluminium) are conductors of heat and electricity and exhibit principles of quantum and solid-state physics.

Q: Can these properties possibly affect drug or chemical equipment design?

A: Yes, stainless steel or titanium is routinely utilised in reactors and pipes based on thermal stability, strength, and corrosion resistance.

Conclusion

Using metal samples in physics-based STEM courses provides a tactile, data-driven learning experience. Students can measure, compare, and test significant material properties influencing engineering and industrial applications. In these experiments, concepts such as density, strength, and conductivity are no longer abstract—they become tangible, measurable, and concrete. Hands-on learning enhances understanding and readiness for application in solving problems in engineering, chemistry, and applied physics.

Additional Resources

•       Stanford Advanced Materials (SAM) – Metal Properties Database

•       Callister, W.D., Materials Science and Engineering: An Introduction, 10th Edition

•       Laboratory Manuals for STEM High School and Undergraduate Physics Programmes

•       Online tutorials: Density, Conductivity, and Thermal Conductivity Experiments