Young’s modulus of a wire

A/L Physics · G.C.E. Advanced Level · Grades 12–13

Aim

To find the Young’s modulus of a metal wire.

Apparatus

• A wire 2.00 m long, 0.50 mm diameter
• Slotted masses (1 kg)
• Micrometer and a vernier scale

Method

1. Measure the diameter with a micrometer and work out the area A.
2. Add loads and record F = mg.
3. Measure the extension e for each load.
4. Plot F against e; E = gradient × L ÷ A.

Conclusion

E = (F ÷ A) ÷ (e ÷ L) = (F ÷ e)(L ÷ A), a property of the material (steel ≈ 200 GPa, copper ≈ 120 GPa).