🔍 Key Concepts

• Relative dielectric constant (relative permittivity) is defined compared to vacuum • Air behaves very similarly to a vacuum for electromagnetic waves at standard conditions • A relative value is usually referenced to a base value of 1 for the reference medium

💭 Think About

• Ask yourself: What is the dielectric constant of a perfect vacuum, and how does air compare to that? • Which choice best represents a medium whose electrical properties are almost the same as empty space? • Would a value of 0 make physical sense for a material’s relative dielectric constant?

✅ Before You Answer

• Remember that relative means "compared to vacuum" so vacuum is the reference value • Check which answers are physically reasonable for a real medium (not zero, not very large for air) • Think about whether air significantly changes capacitance compared to a vacuum or only very slightly