1. What is Relative Permittivity?

Definition: Relative permittivity (ε_r) is a dimensionless number that describes how much a material concentrates electric flux compared to vacuum.

Purpose: It's a crucial parameter in designing capacitors, transmission lines, and other electrical components.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \epsilon_r \) — Relative permittivity (dimensionless)
• \( C \) — Capacitance with material (Farads, F)
• \( C_0 \) — Capacitance in vacuum (Farads, F)

Explanation: The formula compares the capacitance of a capacitor with the material between its plates to the capacitance of the same capacitor with vacuum between its plates.

3. Importance of Relative Permittivity

Details: Relative permittivity affects signal propagation speed, impedance, and energy storage capacity in electrical systems.

4. Using the Calculator

Tips: Measure the capacitance with the material (C) and in vacuum (C₀) using the same capacitor geometry. Enter both values in Farads (F).

5. Frequently Asked Questions (FAQ)

Q1: What are typical values of relative permittivity?
A: Vacuum = 1, Air ≈ 1, Water ≈ 80, Common plastics 2-5, Ceramics 5-1000.

Q2: Why measure in vacuum rather than air?
A: Air's permittivity is very close to vacuum (1.0006), but vacuum provides the purest reference.

Q3: Does relative permittivity vary with frequency?
A: Yes, especially for materials with polar molecules (like water) at high frequencies.

Q4: How do I measure the capacitance values?
A: Use a precision capacitance meter with identical capacitor geometry for both measurements.

Q5: What's the difference between ε_r and absolute permittivity?
A: Absolute permittivity (ε) = ε_r × ε₀, where ε₀ is vacuum permittivity (8.854×10^-12 F/m).