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Difficulty: MediumConductors, Insulators, and Semiconductors

An electrical technician evaluates four material samples of identical length and cross-sectional area under standard test conditions. Arrange these materials in order of their electrical resistance, from lowest resistance (best conductor) to highest resistance (best insulator).

  1. 1Copper wire
  2. 2Nichrome alloy wire
  3. 3Germanium crystal
  4. 4Glass rod

Answer

The correct sequence from lowest resistance to highest resistance is Copper wire, followed by Nichrome alloy wire, then Germanium crystal, and finally Glass rod.
Copper provides the lowest resistance due to abundant free electrons. Nichrome is also a conductor but exhibits higher metallic resistance. Germanium is a semiconductor with intermediate resistance governed by four valence electrons. Glass is an insulator whose tightly bound atomic structure provides the highest resistance.

Step-by-Step Solution

1
Identify and order the metallic conductors based on relative resistivity.
Copper wire has the lowest resistance, followed by Nichrome alloy wire.
Metals have 1 to 3 loosely bound valence electrons that allow free electron movement. Copper is a prime conductor with minimal resistance, whereas Nichrome is an alloy specifically designed to offer higher metallic resistance.
2
Identify the semiconductor and position it after the metallic conductors.
Germanium crystal is placed in the third position.
Semiconductors have four valence electrons forming covalent bonds. Their conductivity is intermediate between conductors and insulators, giving them moderate resistance.
3
Identify the insulator and position it at the end of the sequence.
Glass rod is placed in the final position.
Insulators have tightly bound outer shell electrons and extremely wide energy band gaps, preventing electron flow and producing the highest electrical resistance.

Key Concept

Classification of electrical materials (conductors, semiconductors, and insulators) determined by electron mobility, valence structure, and relative resistance.
Estimated Time:1m 0s
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Topics

Conductors, Insulators, and Semiconductors

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