Which of the following materials is usually a good conductor of electricity and is commonly used for electrical wiring and power cables?

Introduction / Context:
Conductors are materials that allow electric charge to flow through them easily, while insulators do not. In practical electrical work, only a few metals are used widely for wiring and power transmission because they offer a good balance of conductivity, cost and mechanical properties. This question asks which listed material is a good conductor and is commonly used for electrical wiring and cables.

Given Data / Assumptions:

• Aluminium is widely used in overhead power lines and some wiring applications.
• Lead is a metal but has relatively poor electrical conductivity compared with copper and aluminium.
• Nickel is conductive but is used more for plating and special alloys than for bulk wiring.
• Wood is an electrical insulator when dry.

Concept / Approach:
Good electrical conductors have many free electrons and low resistivity. Copper is the standard conductor for household wiring, but aluminium is also widely used, especially in overhead power lines, because it is lightweight, reasonably conductive and less expensive per unit length than copper. Lead, while a metal, has significantly higher resistivity and is used primarily for shielding and batteries rather than as a main conductor. Nickel also conducts electricity but is used mainly in specialised applications due to cost and other properties. Wood, especially when dry, has very high resistivity and is considered an insulator, not a conductor.

Step-by-Step Solution:
Step 1: List the materials and recall their typical uses in electrical engineering.Step 2: Recognise that aluminium is commonly used for power transmission lines and some building wires.Step 3: Note that lead is more commonly used in batteries, cable sheathing and radiation shielding, not as a main current-carrying conductor.Step 4: Recall that nickel is used in alloys, heating elements and plating rather than bulk wiring.Step 5: Recognise that wood is used as an insulating support (for example, poles and structures) because it does not conduct well when dry.Step 6: Conclude that aluminium is the best answer because it is a good conductor widely used for electrical wiring and cables.

Verification / Alternative check:
Look at power lines in many countries: the overhead conductors are typically aluminium or aluminium alloy, sometimes with a steel core for strength. Standard tables of electrical resistivity show that aluminium has low resistivity, only slightly higher than copper. Lead and nickel have significantly higher resistivity and are not economical for large scale wiring. Wood has resistivity many orders of magnitude higher than metals and is treated as an insulator.

Why Other Options Are Wrong:
Lead is not usually chosen for conductors because it is heavy, relatively soft and not particularly good at conducting compared with copper or aluminium. Nickel is conductive but is expensive and used mainly in special alloys and plating, not general wiring. Wood is an insulator in most conditions, especially when dry, and therefore is not suitable for conducting electricity.

Common Pitfalls:
Students may think that any metal is automatically a good conductor for wiring, forgetting that relative conductivity and practical considerations matter. Others might be misled by seeing nickel in coins or lead in cables and assume they are used as conductors. To avoid confusion, remember that copper and aluminium dominate in electrical conductors, while other metals play more specialised roles.

Final Answer:
Aluminium is a good conductor of electricity and is widely used in electrical wiring and power cables.