Which of the following is a semiconductor

Analysis

The question asks us to identify which of the given materials is classified as a semiconductor. To answer this, we need to understand the electrical classification of materials based on their conductivity.

Concept Explanation

Materials are generally classified into three categories based on their ability to conduct electricity:

1. Conductors: These are materials that allow electric current to flow through them easily. They have a high number of free electrons. Examples include metals like copper, iron, aluminum, and gold.
2. Insulators: These are materials that do not allow electric current to flow through them. Their electrons are tightly bound to their atoms. Examples include plastic, rubber, glass, and wood.
3. Semiconductors: These are materials that have electrical conductivity between that of a conductor and an insulator. Their conductivity can be modified by adding impurities (doping) or by changing the temperature. The most common elements used as semiconductors in electronics are Silicon (Si) and Germanium (Ge).

Step-by-Step Solution

• Option A (Copper): Copper is a metal and a very good conductor of electricity. It is used in electrical wiring.
• Option B (Silicon): Silicon is a metalloid. Its atomic structure allows it to act as an insulator at low temperatures and a conductor at higher temperatures or when doped. It is the fundamental material used to manufacture transistors, diodes, and computer chips.
• Option C (Plastic): Plastic is a non-metal and a poor conductor of electricity. It is widely used as an insulator to cover electrical wires.
• Option D (Iron): Iron is a transition metal and a conductor of electricity.

Comparing these to our definition, Silicon is the only material listed that functions as a semiconductor.

Exam Tip

When you see questions about semiconductors in JAMB or WASSCE, always look for Silicon or Germanium. If you see metals like Copper, Iron, or Aluminum, they are conductors; if you see non-metals like Plastic, Wood, or Rubber, they are insulators.