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Materials & Properties

Basic Science & Engineering · Heat, Electricity & Technical Basics

Useful for: Railway RRB, OSSC Science, OSSSC Govt TGT Science — CBZ, OSSSC Govt TGT Science — PCM, SSB TGT CBZ, SSB TGT PCM

Overview

Engineering materials are chosen for properties such as strength, ductility, conductivity and corrosion resistance.

Key points

Ferrous materials contain iron (cast iron, steel); non-ferrous do not (copper, aluminium, brass).
Ductility: drawn into wires; malleability: beaten into sheets; brittleness: breaks without bending.
Copper is used for wires due to high conductivity and ductility.
Aluminium is used for overhead lines because it is light and conducts well.
Cast iron is hard but brittle.

Explanation

Hardness resists scratching; toughness resists breaking under impact.
Elasticity: returns to shape after load is removed.
Stainless steel resists corrosion due to chromium.
Insulators: rubber, PVC, mica, porcelain.

Step by step

Identify the concept, tool or rule involved.
Recall the definition, value or procedure.
Check units, safety logic and the direction of the effect.

Examples

Copper is used for electrical wires because of → high conductivity and ductility.
Cast iron is → brittle.
An insulating material used in electrical equipment → mica.

Traps and advanced points

Trap: Calling cast iron ductile.
Trap: Mixing hardness and toughness.
Trap: Calling brass ferrous.

Quick revision

Ferrous = iron-based.
Ductile = wires; malleable = sheets.
Cr gives stainless steel.

Practice MCQs

Exam practice: Which pigment is primarily responsible for the green colour of plants?
1. Melanin
2. Keratin
3. Chlorophyll
4. Hemoglobin
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Answer: (c) Chlorophyll. Chlorophyll is primarily responsible for the green colour of plants.
Aqua regia is a mixture of concentrated hydrochloric acid and which other acid?
1. Acetic acid
2. Nitric acid
3. Sulfuric acid
4. Carbonic acid
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Answer: (b) Nitric acid. Aqua regia is a mixture of concentrated hydrochloric acid and Nitric acid.
Which is a ferrous material?
1. brass
2. copper
3. aluminium
4. steel
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Answer: (d) steel. Contains iron.
Which is non-ferrous?
1. copper
2. wrought iron
3. cast iron
4. steel
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Answer: (a) copper. No iron.
The property of being drawn into wires is —
1. ductility
2. brittleness
3. elasticity
4. malleability
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Answer: (a) ductility. Ductility.
The property of being beaten into sheets is —
1. malleability
2. hardness
3. brittleness
4. ductility
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Answer: (a) malleability. Malleability.
Copper is used for wires because of high conductivity and —
1. low melting point
2. magnetism
3. brittleness
4. ductility
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Answer: (d) ductility. Ductility.
Aluminium is used in overhead lines because it is —
1. heavy and brittle
2. light and conducts well
3. magnetic
4. cheap only
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Answer: (b) light and conducts well. Light conductor.
Breaking without bending is —
1. malleability
2. brittleness
3. ductility
4. elasticity
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Answer: (b) brittleness. Brittleness.
Steel is mainly an alloy of —
1. zinc and lead
2. iron and carbon
3. copper and tin
4. aluminium and copper
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Answer: (b) iron and carbon. Fe + C.