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The World of Metals and Non-metals - Ductility

Grade 7CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Ductility is the physical property of metals that allows them to be drawn into thin wires without breaking.

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Most metals are ductile, while non-metals are generally non-ductile and brittle (they break when stretched).

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Gold (AuAu) is the most ductile metal. For example, 1 g1\text{ g} of gold can be drawn into a wire of approximately 2 km2\text{ km} in length.

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Copper (CuCu) and Aluminum (AlAl) are commonly used in electrical wiring because of their high ductility and excellent electrical conductivity.

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The property of ductility is used in industrial applications to manufacture wires of various thicknesses, represented by the gauge of the wire.

📐Formulae

Length of wire=Ductility constant×Mass of metal\text{Length of wire} = \text{Ductility constant} \times \text{Mass of metal}

Density (ρ)=mV\text{Density } (\rho) = \frac{m}{V}

Strain=ΔLL\text{Strain} = \frac{\Delta L}{L}

💡Examples

Problem 1:

If 1 gram1\text{ gram} of a highly ductile metal can be drawn into a 2000 m2000\text{ m} wire, calculate the total length of wire that can be produced from 45 grams45\text{ grams} of that metal.

Solution:

L=2000 m/g×45 g=90000 m=90 kmL = 2000\text{ m/g} \times 45\text{ g} = 90000\text{ m} = 90\text{ km}

Explanation:

By multiplying the length produced per unit mass by the total mass, we determine the total potential wire length.

Problem 2:

A technician had a 50000 m50000\text{ m} spool of copper wire. After a project, 12345 m12345\text{ m} of wire was used. Calculate the remaining wire using vertical subtraction.

Solution:

50000−1234537655\begin{array}{r} 50000 \\ - 12345 \\ \hline 37655 \end{array}

Explanation:

The remaining length of the ductile copper wire is 37655 m37655\text{ m} after subtracting the used portion from the initial total.

Problem 3:

Compare the ductility of 10 g10\text{ g} of Gold (AuAu) vs 10 g10\text{ g} of Sulfur (SS).

Solution:

Gold: Drawn into wires≈20 km, Sulfur: Brittle/Powder\text{Gold: Drawn into wires} \approx 20\text{ km}, \text{ Sulfur: Brittle/Powder}

Explanation:

Gold is a metal and highly ductile, allowing it to form long wires. Sulfur is a non-metal and is brittle, meaning it will break or crumble instead of stretching.