Why are metals generally good conductors of electricity?
The correct answer is B: They have many free electrons. Metals are generally good conductors of electricity because they have many free electrons - electrons that are not tightly bound to individual atoms and can move freely through the material.
In metals, the outer electrons of atoms are shared among all atoms in a 'sea of electrons.' These free electrons can move easily when a voltage is applied, creating current flow. This is why metals like copper, aluminum, and silver are excellent conductors - they have many free electrons available to carry current. The more free electrons a material has, the better it conducts electricity. This is why copper wire is used for electrical connections - it has many free electrons and low resistance.
Exam Tip
Good conductors = Many free electrons. Remember: Metals are good conductors because they have many free electrons that can move easily, enabling current flow.
Memory Aid
"**G**ood **C**onductors = **G**reat **C**ollection of **F**ree **E**lectrons (think 'GC = GCFE' = Great Collection of Free Electrons)"
Real-World Application
Copper wire is an excellent conductor because copper atoms have many free electrons. When you connect a battery to a copper wire, the free electrons move easily through the wire, creating current flow. This is why copper is used for power wires, antenna elements, and electrical connections in amateur radio equipment - it conducts electricity well due to its many free electrons.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. High density doesn't make something a good conductor. Some dense materials are insulators. It's the free electrons, not density, that enable conduction.
Option C: Incorrect. Free protons don't exist in normal materials. Protons are in atomic nuclei and don't move. It's free electrons that enable conduction.
Option D: Incorrect. Not all options are correct. Only free electrons enable good conduction.
题目解析
The correct answer is B: They have many free electrons. Metals are generally good conductors of electricity because they have many free electrons - electrons that are not tightly bound to individual atoms and can move freely through the material. In metals, the outer electrons of atoms are shared among all atoms in a 'sea of electrons.' These free electrons can move easily when a voltage is applied, creating current flow. This is why metals like copper, aluminum, and silver are excellent conductors - they have many free electrons available to carry current. The more free electrons a material has, the better it conducts electricity. This is why copper wire is used for electrical connections - it has many free electrons and low resistance.
考试技巧
Good conductors = Many free electrons. Remember: Metals are good conductors because they have many free electrons that can move easily, enabling current flow.
记忆口诀
**G**ood **C**onductors = **G**reat **C**ollection of **F**ree **E**lectrons (think 'GC = GCFE' = Great Collection of Free Electrons)
实际应用示例
Copper wire is an excellent conductor because copper atoms have many free electrons. When you connect a battery to a copper wire, the free electrons move easily through the wire, creating current flow. This is why copper is used for power wires, antenna elements, and electrical connections in amateur radio equipment - it conducts electricity well due to its many free electrons.
错误选项分析
Option A: Incorrect. High density doesn't make something a good conductor. Some dense materials are insulators. It's the free electrons, not density, that enable conduction. Option C: Incorrect. Free protons don't exist in normal materials. Protons are in atomic nuclei and don't move. It's free electrons that enable conduction. Option D: Incorrect. Not all options are correct. Only free electrons enable good conduction.
知识点
Conductors, Free electrons, Metals, Electrical conductivity
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.