Electrical resistivity of rubber (order of magnitude) What is a typical order-of-magnitude value for the resistivity of rubber at room temperature?

Introduction / Context:
Rubber is widely used as an electrical insulator in cables, gloves, and protective coatings. Knowing the order of magnitude of its resistivity helps engineers judge leakage currents, insulation resistance, and safety margins in low- and high-voltage applications.

Given Data / Assumptions:

• Room temperature and dry conditions (moisture greatly lowers surface resistance).
• Bulk resistivity of vulcanized or synthetic rubber compounds.
• DC measurement; AC losses and dielectric constants are secondary here.

Concept / Approach:

Insulating polymers typically have resistivities ranging from 10^8 to well above 10^12 Ω·m depending on formulation and environment. Rubber, especially in dry clean conditions, lies at the high end of this range. Therefore, values around 10^12 Ω·m are representative for order-of-magnitude estimation.

Step-by-Step Solution:

Verification / Alternative check:

Material handbooks show rubber and PTFE in the 10^11–10^14 Ω·m bracket under dry conditions, confirming the selected order.

Why Other Options Are Wrong:

10^2 Ω·m and 10^-2 Ω·m are far too low (approach semiconducting or metallic behavior). 5 × 10^8 Ω·m is possible for contaminated or damp surfaces but is not the typical high-quality bulk value.

Common Pitfalls:

Ignoring humidity and contamination, which reduce surface resistance dramatically; always specify environmental conditions for precise design.

Final Answer:

5 × 10^12 Ω-m