The ability of a substance to resist electrical current flow is described as its Dielectric strength.

• A. Dielectric strength
• B. Conductivity
• C. Resistance
• D. Permittivity

Answer: (A)

Dielectric strength tells you how much electric field a insulating material can withstand before it breaks down and starts conducting in a destructive way. It describes the material’s ability to resist current flow under high voltage, staying an effective insulator up to the breakdown threshold. This is different from conductivity (how easily charges move through a material), resistance (the opposition to current flow in a conductor or path, depending on size and shape), and permittivity (how well a material polarizes to store electric energy). Dielectric strength is usually expressed as breakdown voltage per unit thickness, so the maximum voltage the material can handle equals its dielectric strength times its thickness. For example, a 2 mm layer with a dielectric strength of 20 kV/mm can withstand about 40 kV before breakdown.