The ability of a substance to prevent the flow of electrical current is described as its __________ strength.

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

Answer: (A)

Dielectric strength is the measure of a material’s ability to withstand electric stress without breaking down and starting to conduct current. It directly describes how much voltage per thickness the material can tolerate before insulation fails, so a higher dielectric strength means better protection against unwanted current flow under high voltages. Conductivity describes how easily charges move, which is the opposite idea of preventing flow. Resistance tells you how much a material resists current for a given geometry and voltage, but it doesn’t specify the voltage at which breakdown occurs. Permittivity relates to how a material polarizes and stores energy in an electric field, affecting capacitance rather than its breakdown or insulation performance.